Doc/library/sqlite3.rst
!sqlite3 --- DB-API 2.0 interface for SQLite databases.. module:: sqlite3 :synopsis: A DB-API 2.0 implementation using SQLite 3.x.
Source code: :source:Lib/sqlite3/
.. Make sure we always doctest the tutorial with an empty database.
.. testsetup::
import sqlite3 src = sqlite3.connect(":memory:", isolation_level=None) dst = sqlite3.connect("tutorial.db", isolation_level=None) src.backup(dst) src.close() dst.close() del src, dst
.. _sqlite3-intro:
SQLite is a C library that provides a lightweight disk-based database that doesn't require a separate server process and allows accessing the database using a nonstandard variant of the SQL query language. Some applications can use SQLite for internal data storage. It's also possible to prototype an application using SQLite and then port the code to a larger database such as PostgreSQL or Oracle.
The :mod:!sqlite3 module was written by Gerhard Häring. It provides an SQL interface
compliant with the DB-API 2.0 specification described by :pep:249, and
requires the third-party SQLite <https://sqlite.org/>_ library.
.. include:: ../includes/optional-module.rst
This document includes four main sections:
sqlite3-tutorial teaches how to use the :mod:!sqlite3 module.sqlite3-reference describes the classes and functions this module
defines.sqlite3-howtos details how to handle specific tasks.sqlite3-explanation provides in-depth background on
transaction control... seealso::
https://www.sqlite.org The SQLite web page; the documentation describes the syntax and the available data types for the supported SQL dialect.
https://www.w3schools.com/sql/ Tutorial, reference and examples for learning SQL syntax.
:pep:249 - Database API Specification 2.0
PEP written by Marc-André Lemburg.
.. We use the following practises for SQL code:
.. _sqlite3-tutorial:
In this tutorial, you will create a database of Monty Python movies
using basic :mod:!sqlite3 functionality.
It assumes a fundamental understanding of database concepts,
including cursors_ and transactions_.
First, we need to create a new database and open
a database connection to allow :mod:!sqlite3 to work with it.
Call :func:sqlite3.connect to create a connection to
the database :file:tutorial.db in the current working directory,
implicitly creating it if it does not exist:
.. testcode::
import sqlite3 con = sqlite3.connect("tutorial.db")
The returned :class:Connection object con
represents the connection to the on-disk database.
In order to execute SQL statements and fetch results from SQL queries,
we will need to use a database cursor.
Call :meth:con.cursor() <Connection.cursor> to create the :class:Cursor:
.. testcode::
cur = con.cursor()
Now that we've got a database connection and a cursor,
we can create a database table movie with columns for title,
release year, and review score.
For simplicity, we can just use column names in the table declaration --
thanks to the flexible typing_ feature of SQLite,
specifying the data types is optional.
Execute the CREATE TABLE statement
by calling :meth:cur.execute(...) <Cursor.execute>:
.. testcode::
cur.execute("CREATE TABLE movie(title, year, score)")
.. Ideally, we'd use sqlite_schema instead of sqlite_master below, but SQLite versions older than 3.33.0 do not recognise that variant.
We can verify that the new table has been created by querying
the sqlite_master table built-in to SQLite,
which should now contain an entry for the movie table definition
(see The Schema Table_ for details).
Execute that query by calling :meth:cur.execute(...) <Cursor.execute>,
assign the result to res,
and call :meth:res.fetchone() <Cursor.fetchone> to fetch the resulting row:
.. doctest::
res = cur.execute("SELECT name FROM sqlite_master") res.fetchone() ('movie',)
We can see that the table has been created,
as the query returns a :class:tuple containing the table's name.
If we query sqlite_master for a non-existent table spam,
:meth:!res.fetchone will return None:
.. doctest::
res = cur.execute("SELECT name FROM sqlite_master WHERE name='spam'") res.fetchone() is None True
Now, add two rows of data supplied as SQL literals
by executing an INSERT statement,
once again by calling :meth:cur.execute(...) <Cursor.execute>:
.. testcode::
cur.execute(""" INSERT INTO movie VALUES ('Monty Python and the Holy Grail', 1975, 8.2), ('And Now for Something Completely Different', 1971, 7.5) """)
The INSERT statement implicitly opens a transaction,
which needs to be committed before changes are saved in the database
(see :ref:sqlite3-controlling-transactions for details).
Call :meth:con.commit() <Connection.commit> on the connection object
to commit the transaction:
.. testcode::
con.commit()
We can verify that the data was inserted correctly
by executing a SELECT query.
Use the now-familiar :meth:cur.execute(...) <Cursor.execute> to
assign the result to res,
and call :meth:res.fetchall() <Cursor.fetchall> to return all resulting rows:
.. doctest::
res = cur.execute("SELECT score FROM movie") res.fetchall() [(8.2,), (7.5,)]
The result is a :class:list of two :class:!tuple\s, one per row,
each containing that row's score value.
Now, insert three more rows by calling
:meth:cur.executemany(...) <Cursor.executemany>:
.. testcode::
data = [ ("Monty Python Live at the Hollywood Bowl", 1982, 7.9), ("Monty Python's The Meaning of Life", 1983, 7.5), ("Monty Python's Life of Brian", 1979, 8.0), ] cur.executemany("INSERT INTO movie VALUES(?, ?, ?)", data) con.commit() # Remember to commit the transaction after executing INSERT.
Notice that ? placeholders are used to bind data to the query.
Always use placeholders instead of :ref:string formatting <tut-formatting>
to bind Python values to SQL statements,
to avoid SQL injection attacks_
(see :ref:sqlite3-placeholders for more details).
We can verify that the new rows were inserted
by executing a SELECT query,
this time iterating over the results of the query:
.. doctest::
for row in cur.execute("SELECT year, title FROM movie ORDER BY year"): ... print(row) (1971, 'And Now for Something Completely Different') (1975, 'Monty Python and the Holy Grail') (1979, "Monty Python's Life of Brian") (1982, 'Monty Python Live at the Hollywood Bowl') (1983, "Monty Python's The Meaning of Life")
Each row is a two-item :class:tuple of (year, title),
matching the columns selected in the query.
Finally, verify that the database has been written to disk
by calling :meth:con.close() <Connection.close>
to close the existing connection, opening a new one,
creating a new cursor, then querying the database:
.. doctest::
con.close() new_con = sqlite3.connect("tutorial.db") new_cur = new_con.cursor() res = new_cur.execute("SELECT title, year FROM movie ORDER BY score DESC") title, year = res.fetchone() print(f'The highest scoring Monty Python movie is {title!r}, released in {year}') The highest scoring Monty Python movie is 'Monty Python and the Holy Grail', released in 1975 new_con.close()
You've now created an SQLite database using the :mod:!sqlite3 module,
inserted data and retrieved values from it in multiple ways.
.. _SQL injection attacks: https://en.wikipedia.org/wiki/SQL_injection .. _The Schema Table: https://www.sqlite.org/schematab.html .. _cursors: https://en.wikipedia.org/wiki/Cursor_(databases) .. _flexible typing: https://www.sqlite.org/flextypegood.html .. _sqlite_master: https://www.sqlite.org/schematab.html .. _transactions: https://en.wikipedia.org/wiki/Database_transaction
.. seealso::
:ref:sqlite3-howtos for further reading:
sqlite3-placeholderssqlite3-adapterssqlite3-converterssqlite3-connection-context-managersqlite3-howto-row-factory:ref:sqlite3-explanation for in-depth background on transaction control.
.. _sqlite3-reference:
.. We keep the old sqlite3-module-contents ref to prevent breaking links. .. _sqlite3-module-contents:
.. _sqlite3-module-functions:
Module functions ^^^^^^^^^^^^^^^^
.. function:: connect(database, *, timeout=5.0, detect_types=0,
isolation_level="DEFERRED", check_same_thread=True,
factory=sqlite3.Connection, cached_statements=128,
uri=False,
autocommit=sqlite3.LEGACY_TRANSACTION_CONTROL)
Open a connection to an SQLite database.
:param database:
The path to the database file to be opened.
You can pass ":memory:" to create an SQLite database existing only in memory <https://sqlite.org/inmemorydb.html>_, and open a connection
to it.
:type database: :term:path-like object
:param float timeout:
How many seconds the connection should wait before raising
an :exc:OperationalError when a table is locked.
If another connection opens a transaction to modify a table,
that table will be locked until the transaction is committed.
Default five seconds.
:param int detect_types:
Control whether and how data types not
:ref:natively supported by SQLite <sqlite3-types>
are looked up to be converted to Python types,
using the converters registered with :func:register_converter.
Set it to any combination (using |, bitwise or) of
:const:PARSE_DECLTYPES and :const:PARSE_COLNAMES
to enable this.
Column names take precedence over declared types if both flags are set.
By default (0), type detection is disabled.
:param isolation_level:
Control legacy transaction handling behaviour.
See :attr:Connection.isolation_level and
:ref:sqlite3-transaction-control-isolation-level for more information.
Can be "DEFERRED" (default), "EXCLUSIVE" or "IMMEDIATE";
or None to disable opening transactions implicitly.
Has no effect unless :attr:Connection.autocommit is set to
:const:~sqlite3.LEGACY_TRANSACTION_CONTROL (the default).
:type isolation_level: str | None
:param bool check_same_thread:
If True (default), :exc:ProgrammingError will be raised
if the database connection is used by a thread
other than the one that created it.
If False, the connection may be accessed in multiple threads;
write operations may need to be serialized by the user
to avoid data corruption.
See :attr:threadsafety for more information.
:param ~sqlite3.Connection factory:
A custom subclass of :class:Connection to create the connection with,
if not the default :class:Connection class.
:param int cached_statements:
The number of statements that :mod:!sqlite3
should internally cache for this connection, to avoid parsing overhead.
By default, 128 statements.
:param bool uri:
If set to True, database is interpreted as a
:abbr:URI (Uniform Resource Identifier) with a file path
and an optional query string.
The scheme part must be "file:",
and the path can be relative or absolute.
The query string allows passing parameters to SQLite,
enabling various :ref:sqlite3-uri-tricks.
:param autocommit:
Control :pep:249 transaction handling behaviour.
See :attr:Connection.autocommit and
:ref:sqlite3-transaction-control-autocommit for more information.
autocommit currently defaults to
:const:~sqlite3.LEGACY_TRANSACTION_CONTROL.
The default will change to False in a future Python release.
:type autocommit: bool
:rtype: ~sqlite3.Connection
.. audit-event:: sqlite3.connect database sqlite3.connect .. audit-event:: sqlite3.connect/handle connection_handle sqlite3.connect
.. versionchanged:: 3.4 Added the uri parameter.
.. versionchanged:: 3.7
database can now also be a :term:path-like object, not only a string.
.. versionchanged:: 3.10
Added the sqlite3.connect/handle auditing event.
.. versionchanged:: 3.12 Added the autocommit parameter.
.. versionchanged:: 3.15 All parameters except database are now keyword-only.
.. function:: complete_statement(statement)
Return True if the string statement appears to contain
one or more complete SQL statements.
No syntactic verification or parsing of any kind is performed,
other than checking that there are no unclosed string literals
and the statement is terminated by a semicolon.
For example:
.. doctest::
>>> sqlite3.complete_statement("SELECT foo FROM bar;")
True
>>> sqlite3.complete_statement("SELECT foo")
False
This function may be useful during command-line input
to determine if the entered text seems to form a complete SQL statement,
or if additional input is needed before calling :meth:~Cursor.execute.
See :func:!runsource in :source:Lib/sqlite3/__main__.py
for real-world use.
.. function:: enable_callback_tracebacks(flag, /)
Enable or disable callback tracebacks.
By default you will not get any tracebacks in user-defined functions,
aggregates, converters, authorizer callbacks etc. If you want to debug them,
you can call this function with flag set to True. Afterwards, you
will get tracebacks from callbacks on :data:sys.stderr. Use False
to disable the feature again.
.. note::
Errors in user-defined function callbacks are logged as unraisable exceptions.
Use an :func:`unraisable hook handler <sys.unraisablehook>` for
introspection of the failed callback.
.. function:: register_adapter(type, adapter, /)
Register an adapter :term:callable to adapt the Python type type
into an SQLite type.
The adapter is called with a Python object of type type as its sole
argument, and must return a value of a
:ref:type that SQLite natively understands <sqlite3-types>.
.. function:: register_converter(typename, converter, /)
Register the converter :term:callable to convert SQLite objects of type
typename into a Python object of a specific type.
The converter is invoked for all SQLite values of type typename;
it is passed a :class:bytes object and should return an object of the
desired Python type.
Consult the parameter detect_types of
:func:connect for information regarding how type detection works.
Note: typename and the name of the type in your query are matched case-insensitively.
.. _sqlite3-module-constants:
Module constants ^^^^^^^^^^^^^^^^
.. data:: LEGACY_TRANSACTION_CONTROL
Set :attr:~Connection.autocommit to this constant to select
old style (pre-Python 3.12) transaction control behaviour.
See :ref:sqlite3-transaction-control-isolation-level for more information.
.. data:: PARSE_DECLTYPES
Pass this flag value to the detect_types parameter of
:func:connect to look up a converter function using
the declared types for each column.
The types are declared when the database table is created.
:mod:!sqlite3 will look up a converter function using the first word of the
declared type as the converter dictionary key.
For example:
.. code-block:: sql
CREATE TABLE test(
i integer primary key, ! will look up a converter named "integer"
p point, ! will look up a converter named "point"
n number(10) ! will look up a converter named "number"
)
This flag may be combined with :const:PARSE_COLNAMES using the |
(bitwise or) operator.
.. note::
Generated fields (for example ``MAX(p)``) are returned as :class:`str`.
Use :const:`!PARSE_COLNAMES` to enforce types for such queries.
.. data:: PARSE_COLNAMES
Pass this flag value to the detect_types parameter of
:func:connect to look up a converter function by
using the type name, parsed from the query column name,
as the converter dictionary key.
The query column name must be wrapped in double quotes (")
and the type name must be wrapped in square brackets ([]).
.. code-block:: sql
SELECT MAX(p) as "p [point]" FROM test; ! will look up converter "point"
This flag may be combined with :const:PARSE_DECLTYPES using the |
(bitwise or) operator.
.. data:: SQLITE_OK SQLITE_DENY SQLITE_IGNORE
Flags that should be returned by the authorizer_callback :term:callable
passed to :meth:Connection.set_authorizer, to indicate whether:
!SQLITE_OK),!SQLITE_DENY)NULL value (:const:!SQLITE_IGNORE).. data:: apilevel
String constant stating the supported DB-API level. Required by the DB-API.
Hard-coded to "2.0".
.. data:: paramstyle
String constant stating the type of parameter marker formatting expected by
the :mod:!sqlite3 module. Required by the DB-API. Hard-coded to
"qmark".
.. note::
The ``named`` DB-API parameter style is also supported.
.. data:: sqlite_version
Version number of the runtime SQLite library as a :class:string <str>.
.. data:: sqlite_version_info
Version number of the runtime SQLite library as a :class:tuple of
:class:integers <int>.
.. data:: SQLITE_KEYWORDS
A :class:tuple containing all SQLite keywords.
This constant is only available if Python was compiled with SQLite 3.24.0 or greater.
.. versionadded:: 3.15
.. data:: threadsafety
Integer constant required by the DB-API 2.0, stating the level of thread
safety the :mod:!sqlite3 module supports. This attribute is set based on
the default threading mode <https://sqlite.org/threadsafe.html>_ the
underlying SQLite library is compiled with. The SQLite threading modes are:
The mappings from SQLite threading modes to DB-API 2.0 threadsafety levels are as follows:
+------------------+----------------------+----------------------+-------------------------------+
| SQLite threading | :pep:threadsafety | SQLITE_THREADSAFE_ | DB-API 2.0 meaning | | mode | <0249#threadsafety> | | |
+==================+======================+======================+===============================+
| single-thread | 0 | 0 | Threads may not share the |
| | | | module |
+------------------+----------------------+----------------------+-------------------------------+
| multi-thread | 1 | 2 | Threads may share the module, |
| | | | but not connections |
+------------------+----------------------+----------------------+-------------------------------+
| serialized | 3 | 1 | Threads may share the module, |
| | | | connections and cursors |
+------------------+----------------------+----------------------+-------------------------------+
.. _SQLITE_THREADSAFE: https://sqlite.org/compile.html#threadsafe
.. versionchanged:: 3.11
Set threadsafety dynamically instead of hard-coding it to 1.
.. _sqlite3-dbconfig-constants:
.. data:: SQLITE_DBCONFIG_DEFENSIVE SQLITE_DBCONFIG_DQS_DDL SQLITE_DBCONFIG_DQS_DML SQLITE_DBCONFIG_ENABLE_FKEY SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION SQLITE_DBCONFIG_ENABLE_QPSG SQLITE_DBCONFIG_ENABLE_TRIGGER SQLITE_DBCONFIG_ENABLE_VIEW SQLITE_DBCONFIG_LEGACY_ALTER_TABLE SQLITE_DBCONFIG_LEGACY_FILE_FORMAT SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE SQLITE_DBCONFIG_RESET_DATABASE SQLITE_DBCONFIG_TRIGGER_EQP SQLITE_DBCONFIG_TRUSTED_SCHEMA SQLITE_DBCONFIG_WRITABLE_SCHEMA
These constants are used for the :meth:Connection.setconfig
and :meth:~Connection.getconfig methods.
The availability of these constants varies depending on the version of SQLite Python was compiled with.
.. versionadded:: 3.12
.. seealso::
https://www.sqlite.org/c3ref/c_dbconfig_defensive.html
SQLite docs: Database Connection Configuration Options
.. deprecated-removed:: 3.12 3.14
The :data:!version and :data:!version_info constants.
.. _sqlite3-connection-objects:
Connection objects ^^^^^^^^^^^^^^^^^^
.. class:: Connection
Each open SQLite database is represented by a Connection object,
which is created using :func:sqlite3.connect.
Their main purpose is creating :class:Cursor objects,
and :ref:sqlite3-controlling-transactions.
.. seealso::
* :ref:`sqlite3-connection-shortcuts`
* :ref:`sqlite3-connection-context-manager`
.. versionchanged:: 3.13
A :exc:`ResourceWarning` is emitted if :meth:`close` is not called before
a :class:`!Connection` object is deleted.
An SQLite database connection has the following attributes and methods:
.. method:: cursor(factory=Cursor)
Create and return a :class:`Cursor` object.
The cursor method accepts a single optional parameter *factory*. If
supplied, this must be a :term:`callable` returning
an instance of :class:`Cursor` or its subclasses.
.. method:: blobopen(table, column, rowid, /, *, readonly=False, name="main")
Open a :class:`Blob` handle to an existing
:abbr:`BLOB (Binary Large OBject)`.
:param str table:
The name of the table where the blob is located.
:param str column:
The name of the column where the blob is located.
:param int rowid:
The row id where the blob is located.
:param bool readonly:
Set to ``True`` if the blob should be opened without write
permissions.
Defaults to ``False``.
:param str name:
The name of the database where the blob is located.
Defaults to ``"main"``.
:raises OperationalError:
When trying to open a blob in a ``WITHOUT ROWID`` table.
:rtype: Blob
.. note::
The blob size cannot be changed using the :class:`Blob` class.
Use the SQL function ``zeroblob`` to create a blob with a fixed size.
.. versionadded:: 3.11
.. method:: commit()
Commit any pending transaction to the database.
If :attr:`autocommit` is ``True``, or there is no open transaction,
this method does nothing.
If :attr:`!autocommit` is ``False``, a new transaction is implicitly
opened if a pending transaction was committed by this method.
.. method:: rollback()
Roll back to the start of any pending transaction.
If :attr:`autocommit` is ``True``, or there is no open transaction,
this method does nothing.
If :attr:`!autocommit` is ``False``, a new transaction is implicitly
opened if a pending transaction was rolled back by this method.
.. method:: close()
Close the database connection.
If :attr:`autocommit` is ``False``,
any pending transaction is implicitly rolled back.
If :attr:`!autocommit` is ``True`` or :data:`LEGACY_TRANSACTION_CONTROL`,
no implicit transaction control is executed.
Make sure to :meth:`commit` before closing
to avoid losing pending changes.
.. method:: execute(sql, parameters=(), /)
Create a new :class:`Cursor` object and call
:meth:`~Cursor.execute` on it with the given *sql* and *parameters*.
Return the new cursor object.
.. method:: executemany(sql, parameters, /)
Create a new :class:`Cursor` object and call
:meth:`~Cursor.executemany` on it with the given *sql* and *parameters*.
Return the new cursor object.
.. method:: executescript(sql_script, /)
Create a new :class:`Cursor` object and call
:meth:`~Cursor.executescript` on it with the given *sql_script*.
Return the new cursor object.
.. method:: create_function(name, narg, func, /, *, deterministic=False)
Create or remove a user-defined SQL function.
:param str name:
The name of the SQL function.
:param int narg:
The number of arguments the SQL function can accept.
If ``-1``, it may take any number of arguments.
:param func:
A :term:`callable` that is called when the SQL function is invoked.
The callable must return :ref:`a type natively supported by SQLite
<sqlite3-types>`.
Set to ``None`` to remove an existing SQL function.
:type func: :term:`callback` | None
:param bool deterministic:
If ``True``, the created SQL function is marked as
`deterministic <https://sqlite.org/deterministic.html>`_,
which allows SQLite to perform additional optimizations.
.. versionchanged:: 3.8
Added the *deterministic* parameter.
.. versionchanged:: 3.15
The first three parameters are now positional-only.
Example:
.. doctest::
>>> import hashlib
>>> def md5sum(t):
... return hashlib.md5(t).hexdigest()
>>> con = sqlite3.connect(":memory:")
>>> con.create_function("md5", 1, md5sum)
>>> for row in con.execute("SELECT md5(?)", (b"foo",)):
... print(row)
('acbd18db4cc2f85cedef654fccc4a4d8',)
>>> con.close()
.. method:: create_aggregate(name, n_arg, aggregate_class, /)
Create or remove a user-defined SQL aggregate function.
:param str name:
The name of the SQL aggregate function.
:param int n_arg:
The number of arguments the SQL aggregate function can accept.
If ``-1``, it may take any number of arguments.
:param aggregate_class:
A class must implement the following methods:
* ``step()``: Add a row to the aggregate.
* ``finalize()``: Return the final result of the aggregate as
:ref:`a type natively supported by SQLite <sqlite3-types>`.
The number of arguments that the ``step()`` method must accept
is controlled by *n_arg*.
Set to ``None`` to remove an existing SQL aggregate function.
:type aggregate_class: :term:`class` | None
.. versionchanged:: 3.15
All three parameters are now positional-only.
Example:
.. testcode::
class MySum:
def __init__(self):
self.count = 0
def step(self, value):
self.count += value
def finalize(self):
return self.count
con = sqlite3.connect(":memory:")
con.create_aggregate("mysum", 1, MySum)
cur = con.execute("CREATE TABLE test(i)")
cur.execute("INSERT INTO test(i) VALUES(1)")
cur.execute("INSERT INTO test(i) VALUES(2)")
cur.execute("SELECT mysum(i) FROM test")
print(cur.fetchone()[0])
con.close()
.. testoutput::
:hide:
3
.. method:: create_window_function(name, num_params, aggregate_class, /)
Create or remove a user-defined aggregate window function.
:param str name:
The name of the SQL aggregate window function to create or remove.
:param int num_params:
The number of arguments the SQL aggregate window function can accept.
If ``-1``, it may take any number of arguments.
:param aggregate_class:
A class that must implement the following methods:
* ``step()``: Add a row to the current window.
* ``value()``: Return the current value of the aggregate.
* ``inverse()``: Remove a row from the current window.
* ``finalize()``: Return the final result of the aggregate as
:ref:`a type natively supported by SQLite <sqlite3-types>`.
The number of arguments that the ``step()`` and ``value()`` methods
must accept is controlled by *num_params*.
Set to ``None`` to remove an existing SQL aggregate window function.
:raises NotSupportedError:
If used with a version of SQLite older than 3.25.0,
which does not support aggregate window functions.
:type aggregate_class: :term:`class` | None
.. versionadded:: 3.11
Example:
.. testcode::
# Example taken from https://www.sqlite.org/windowfunctions.html#udfwinfunc
class WindowSumInt:
def __init__(self):
self.count = 0
def step(self, value):
"""Add a row to the current window."""
self.count += value
def value(self):
"""Return the current value of the aggregate."""
return self.count
def inverse(self, value):
"""Remove a row from the current window."""
self.count -= value
def finalize(self):
"""Return the final value of the aggregate.
Any clean-up actions should be placed here.
"""
return self.count
con = sqlite3.connect(":memory:")
cur = con.execute("CREATE TABLE test(x, y)")
values = [
("a", 4),
("b", 5),
("c", 3),
("d", 8),
("e", 1),
]
cur.executemany("INSERT INTO test VALUES(?, ?)", values)
con.create_window_function("sumint", 1, WindowSumInt)
cur.execute("""
SELECT x, sumint(y) OVER (
ORDER BY x ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING
) AS sum_y
FROM test ORDER BY x
""")
print(cur.fetchall())
con.close()
.. testoutput::
:hide:
[('a', 9), ('b', 12), ('c', 16), ('d', 12), ('e', 9)]
.. method:: create_collation(name, callable, /)
Create a collation named *name* using the collating function *callable*.
*callable* is passed two :class:`string <str>` arguments,
and it should return an :class:`integer <int>`:
* ``1`` if the first is ordered higher than the second
* ``-1`` if the first is ordered lower than the second
* ``0`` if they are ordered equal
The following example shows a reverse sorting collation:
.. testcode::
def collate_reverse(string1, string2):
if string1 == string2:
return 0
elif string1 < string2:
return 1
else:
return -1
con = sqlite3.connect(":memory:")
con.create_collation("reverse", collate_reverse)
cur = con.execute("CREATE TABLE test(x)")
cur.executemany("INSERT INTO test(x) VALUES(?)", [("a",), ("b",)])
cur.execute("SELECT x FROM test ORDER BY x COLLATE reverse")
for row in cur:
print(row)
con.close()
.. testoutput::
:hide:
('b',)
('a',)
Remove a collation function by setting *callable* to ``None``.
.. versionchanged:: 3.11
The collation name can contain any Unicode character. Earlier, only
ASCII characters were allowed.
.. method:: interrupt()
Call this method from a different thread to abort any queries that might
be executing on the connection.
Aborted queries will raise an :exc:`OperationalError`.
.. method:: set_authorizer(authorizer_callback, /)
Register :term:`callable` *authorizer_callback* to be invoked
for each attempt to access a column of a table in the database.
The callback should return one of :const:`SQLITE_OK`,
:const:`SQLITE_DENY`, or :const:`SQLITE_IGNORE`
to signal how access to the column should be handled
by the underlying SQLite library.
The first argument to the callback signifies what kind of operation is to be
authorized. The second and third argument will be arguments or ``None``
depending on the first argument. The 4th argument is the name of the database
("main", "temp", etc.) if applicable. The 5th argument is the name of the
inner-most trigger or view that is responsible for the access attempt or
``None`` if this access attempt is directly from input SQL code.
Please consult the SQLite documentation about the possible values for the first
argument and the meaning of the second and third argument depending on the first
one. All necessary constants are available in the :mod:`!sqlite3` module.
Passing ``None`` as *authorizer_callback* will disable the authorizer.
.. versionchanged:: 3.11
Added support for disabling the authorizer using ``None``.
.. versionchanged:: 3.15
The only parameter is now positional-only.
.. method:: set_progress_handler(progress_handler, /, n)
Register :term:`callable` *progress_handler* to be invoked for every *n*
instructions of the SQLite virtual machine. This is useful if you want to
get called from SQLite during long-running operations, for example to update
a GUI.
If you want to clear any previously installed progress handler, call the
method with ``None`` for *progress_handler*.
Returning a non-zero value from the handler function will terminate the
currently executing query and cause it to raise a :exc:`DatabaseError`
exception.
.. versionchanged:: 3.15
The first parameter is now positional-only.
.. method:: set_trace_callback(trace_callback, /)
Register :term:`callable` *trace_callback* to be invoked
for each SQL statement that is actually executed by the SQLite backend.
The only argument passed to the callback is the statement (as
:class:`str`) that is being executed. The return value of the callback is
ignored. Note that the backend does not only run statements passed to the
:meth:`Cursor.execute` methods. Other sources include the
:ref:`transaction management <sqlite3-controlling-transactions>` of the
:mod:`!sqlite3` module and the execution of triggers defined in the current
database.
Passing ``None`` as *trace_callback* will disable the trace callback.
.. note::
Exceptions raised in the trace callback are not propagated. As a
development and debugging aid, use
:meth:`~sqlite3.enable_callback_tracebacks` to enable printing
tracebacks from exceptions raised in the trace callback.
.. versionadded:: 3.3
.. versionchanged:: 3.15
The first parameter is now positional-only.
.. method:: enable_load_extension(enabled, /)
Enable the SQLite engine to load SQLite extensions from shared libraries
if *enabled* is ``True``;
else, disallow loading SQLite extensions.
SQLite extensions can define new functions,
aggregates or whole new virtual table implementations. One well-known
extension is the fulltext-search extension distributed with SQLite.
.. note::
The :mod:`!sqlite3` module is not built with loadable extension support by
default, because some platforms (notably macOS) have SQLite
libraries which are compiled without this feature.
To get loadable extension support,
you must pass the :option:`--enable-loadable-sqlite-extensions` option
to :program:`configure`.
.. audit-event:: sqlite3.enable_load_extension connection,enabled sqlite3.Connection.enable_load_extension
.. versionadded:: 3.2
.. versionchanged:: 3.10
Added the ``sqlite3.enable_load_extension`` auditing event.
.. We cannot doctest the load extension API, since there is no convenient
way to skip it.
.. code-block::
con.enable_load_extension(True)
# Load the fulltext search extension
con.execute("select load_extension('./fts3.so')")
# alternatively you can load the extension using an API call:
# con.load_extension("./fts3.so")
# disable extension loading again
con.enable_load_extension(False)
# example from SQLite wiki
con.execute("CREATE VIRTUAL TABLE recipe USING fts3(name, ingredients)")
con.executescript("""
INSERT INTO recipe (name, ingredients) VALUES('broccoli stew', 'broccoli peppers cheese tomatoes');
INSERT INTO recipe (name, ingredients) VALUES('pumpkin stew', 'pumpkin onions garlic celery');
INSERT INTO recipe (name, ingredients) VALUES('broccoli pie', 'broccoli cheese onions flour');
INSERT INTO recipe (name, ingredients) VALUES('pumpkin pie', 'pumpkin sugar flour butter');
""")
for row in con.execute("SELECT rowid, name, ingredients FROM recipe WHERE name MATCH 'pie'"):
print(row)
.. method:: load_extension(path, /, *, entrypoint=None)
Load an SQLite extension from a shared library.
Enable extension loading with :meth:`enable_load_extension` before
calling this method.
:param str path:
The path to the SQLite extension.
:param entrypoint:
Entry point name.
If ``None`` (the default),
SQLite will come up with an entry point name of its own;
see the SQLite docs `Loading an Extension`_ for details.
:type entrypoint: str | None
.. audit-event:: sqlite3.load_extension connection,path sqlite3.Connection.load_extension
.. versionadded:: 3.2
.. versionchanged:: 3.10
Added the ``sqlite3.load_extension`` auditing event.
.. versionchanged:: 3.12
Added the *entrypoint* parameter.
.. _Loading an Extension: https://www.sqlite.org/loadext.html#loading_an_extension
.. method:: iterdump(*, filter=None)
Return an :term:`iterator` to dump the database as SQL source code.
Useful when saving an in-memory database for later restoration.
Similar to the ``.dump`` command in the :program:`sqlite3` shell.
:param filter:
An optional ``LIKE`` pattern for database objects to dump, e.g. ``prefix_%``.
If ``None`` (the default), all database objects will be included.
:type filter: str | None
Example:
.. testcode::
# Convert file example.db to SQL dump file dump.sql
con = sqlite3.connect('example.db')
with open('dump.sql', 'w') as f:
for line in con.iterdump():
f.write('%s\n' % line)
con.close()
.. seealso::
:ref:`sqlite3-howto-encoding`
.. versionchanged:: 3.13
Added the *filter* parameter.
.. method:: backup(target, *, pages=-1, progress=None, name="main", sleep=0.250)
Create a backup of an SQLite database.
Works even if the database is being accessed by other clients
or concurrently by the same connection.
:param ~sqlite3.Connection target:
The database connection to save the backup to.
:param int pages:
The number of pages to copy at a time.
If equal to or less than ``0``,
the entire database is copied in a single step.
Defaults to ``-1``.
:param progress:
If set to a :term:`callable`,
it is invoked with three integer arguments for every backup iteration:
the *status* of the last iteration,
the *remaining* number of pages still to be copied,
and the *total* number of pages.
Defaults to ``None``.
:type progress: :term:`callback` | None
:param str name:
The name of the database to back up.
Either ``"main"`` (the default) for the main database,
``"temp"`` for the temporary database,
or the name of a custom database as attached using the
``ATTACH DATABASE`` SQL statement.
:param float sleep:
The number of seconds to sleep between successive attempts
to back up remaining pages.
Example 1, copy an existing database into another:
.. testcode::
def progress(status, remaining, total):
print(f'Copied {total-remaining} of {total} pages...')
src = sqlite3.connect('example.db')
dst = sqlite3.connect('backup.db')
with dst:
src.backup(dst, pages=1, progress=progress)
dst.close()
src.close()
.. testoutput::
:hide:
Copied 0 of 0 pages...
Example 2, copy an existing database into a transient copy:
.. testcode::
src = sqlite3.connect('example.db')
dst = sqlite3.connect(':memory:')
src.backup(dst)
dst.close()
src.close()
.. versionadded:: 3.7
.. seealso::
:ref:`sqlite3-howto-encoding`
.. method:: getlimit(category, /)
Get a connection runtime limit.
:param int category:
The `SQLite limit category`_ to be queried.
:rtype: int
:raises ProgrammingError:
If *category* is not recognised by the underlying SQLite library.
Example, query the maximum length of an SQL statement
for :class:`Connection` ``con`` (the default is 1000000000):
.. testsetup:: sqlite3.limits
import sqlite3
con = sqlite3.connect(":memory:")
con.setlimit(sqlite3.SQLITE_LIMIT_SQL_LENGTH, 1_000_000_000)
con.setlimit(sqlite3.SQLITE_LIMIT_ATTACHED, 10)
.. doctest:: sqlite3.limits
>>> con.getlimit(sqlite3.SQLITE_LIMIT_SQL_LENGTH)
1000000000
.. versionadded:: 3.11
.. method:: setlimit(category, limit, /)
Set a connection runtime limit.
Attempts to increase a limit above its hard upper bound are silently
truncated to the hard upper bound. Regardless of whether or not the limit
was changed, the prior value of the limit is returned.
:param int category:
The `SQLite limit category`_ to be set.
:param int limit:
The value of the new limit.
If negative, the current limit is unchanged.
:rtype: int
:raises ProgrammingError:
If *category* is not recognised by the underlying SQLite library.
Example, limit the number of attached databases to 1
for :class:`Connection` ``con`` (the default limit is 10):
.. doctest:: sqlite3.limits
>>> con.setlimit(sqlite3.SQLITE_LIMIT_ATTACHED, 1)
10
>>> con.getlimit(sqlite3.SQLITE_LIMIT_ATTACHED)
1
.. testcleanup:: sqlite3.limits
con.close()
.. versionadded:: 3.11
.. _SQLite limit category: https://www.sqlite.org/c3ref/c_limit_attached.html
.. method:: getconfig(op, /)
Query a boolean connection configuration option.
:param int op:
A :ref:`SQLITE_DBCONFIG code <sqlite3-dbconfig-constants>`.
:rtype: bool
.. versionadded:: 3.12
.. method:: setconfig(op, enable=True, /)
Set a boolean connection configuration option.
:param int op:
A :ref:`SQLITE_DBCONFIG code <sqlite3-dbconfig-constants>`.
:param bool enable:
``True`` if the configuration option should be enabled (default);
``False`` if it should be disabled.
.. versionadded:: 3.12
.. method:: serialize(*, name="main")
Serialize a database into a :class:`bytes` object. For an
ordinary on-disk database file, the serialization is just a copy of the
disk file. For an in-memory database or a "temp" database, the
serialization is the same sequence of bytes which would be written to
disk if that database were backed up to disk.
:param str name:
The database name to be serialized.
Defaults to ``"main"``.
:rtype: bytes
.. note::
This method is only available if the underlying SQLite library has the
serialize API.
.. versionadded:: 3.11
.. method:: deserialize(data, /, *, name="main")
Deserialize a :meth:`serialized <serialize>` database into a
:class:`Connection`.
This method causes the database connection to disconnect from database
*name*, and reopen *name* as an in-memory database based on the
serialization contained in *data*.
:param bytes data:
A serialized database.
:param str name:
The database name to deserialize into.
Defaults to ``"main"``.
:raises OperationalError:
If the database connection is currently involved in a read
transaction or a backup operation.
:raises DatabaseError:
If *data* does not contain a valid SQLite database.
:raises OverflowError:
If :func:`len(data) <len>` is larger than ``2**63 - 1``.
.. note::
This method is only available if the underlying SQLite library has the
deserialize API.
.. versionadded:: 3.11
.. attribute:: autocommit
This attribute controls :pep:`249`-compliant transaction behaviour.
:attr:`!autocommit` has three allowed values:
* ``False``: Select :pep:`249`-compliant transaction behaviour,
implying that :mod:`!sqlite3` ensures a transaction is always open.
Use :meth:`commit` and :meth:`rollback` to close transactions.
This is the recommended value of :attr:`!autocommit`.
* ``True``: Use SQLite's `autocommit mode`_.
:meth:`commit` and :meth:`rollback` have no effect in this mode.
* :data:`LEGACY_TRANSACTION_CONTROL`:
Pre-Python 3.12 (non-:pep:`249`-compliant) transaction control.
See :attr:`isolation_level` for more details.
This is currently the default value of :attr:`!autocommit`.
Changing :attr:`!autocommit` to ``False`` will open a new transaction,
and changing it to ``True`` will commit any pending transaction.
See :ref:`sqlite3-transaction-control-autocommit` for more details.
.. note::
The :attr:`isolation_level` attribute has no effect unless
:attr:`autocommit` is :data:`LEGACY_TRANSACTION_CONTROL`.
.. versionadded:: 3.12
.. attribute:: in_transaction
This read-only attribute corresponds to the low-level SQLite
`autocommit mode`_.
``True`` if a transaction is active (there are uncommitted changes),
``False`` otherwise.
.. versionadded:: 3.2
.. attribute:: isolation_level
Controls the :ref:`legacy transaction handling mode
<sqlite3-transaction-control-isolation-level>` of :mod:`!sqlite3`.
If set to ``None``, transactions are never implicitly opened.
If set to one of ``"DEFERRED"``, ``"IMMEDIATE"``, or ``"EXCLUSIVE"``,
corresponding to the underlying `SQLite transaction behaviour`_,
:ref:`implicit transaction management
<sqlite3-transaction-control-isolation-level>` is performed.
If not overridden by the *isolation_level* parameter of :func:`connect`,
the default is ``""``, which is an alias for ``"DEFERRED"``.
.. note::
Using :attr:`autocommit` to control transaction handling is
recommended over using :attr:`!isolation_level`.
:attr:`!isolation_level` has no effect unless :attr:`autocommit` is
set to :data:`LEGACY_TRANSACTION_CONTROL` (the default).
.. attribute:: row_factory
The initial :attr:`~Cursor.row_factory`
for :class:`Cursor` objects created from this connection.
Assigning to this attribute does not affect the :attr:`!row_factory`
of existing cursors belonging to this connection, only new ones.
Is ``None`` by default,
meaning each row is returned as a :class:`tuple`.
See :ref:`sqlite3-howto-row-factory` for more details.
.. attribute:: text_factory
A :term:`callable` that accepts a :class:`bytes` parameter
and returns a text representation of it.
The callable is invoked for SQLite values with the ``TEXT`` data type.
By default, this attribute is set to :class:`str`.
See :ref:`sqlite3-howto-encoding` for more details.
.. attribute:: total_changes
Return the total number of database rows that have been modified, inserted, or
deleted since the database connection was opened.
.. _sqlite3-cursor-objects:
Cursor objects ^^^^^^^^^^^^^^
A Cursor object represents a database cursor_
which is used to execute SQL statements,
and manage the context of a fetch operation.
Cursors are created using :meth:Connection.cursor,
or by using any of the :ref:connection shortcut methods <sqlite3-connection-shortcuts>.
Cursor objects are :term:iterators <iterator>,
meaning that if you :meth:~Cursor.execute a SELECT query,
you can simply iterate over the cursor to fetch the resulting rows:
.. testsetup:: sqlite3.cursor
import sqlite3
con = sqlite3.connect(":memory:", isolation_level=None)
cur = con.execute("CREATE TABLE data(t)")
cur.execute("INSERT INTO data VALUES(1)")
.. testcode:: sqlite3.cursor
for row in cur.execute("SELECT t FROM data"):
print(row)
.. testoutput:: sqlite3.cursor :hide:
(1,)
.. _database cursor: https://en.wikipedia.org/wiki/Cursor_(databases)
.. class:: Cursor
A :class:Cursor instance has the following attributes and methods.
.. index:: single: ? (question mark); in SQL statements .. index:: single: : (colon); in SQL statements
.. method:: execute(sql, parameters=(), /)
Execute a single SQL statement,
optionally binding Python values using
:ref:`placeholders <sqlite3-placeholders>`.
:param str sql:
A single SQL statement.
:param parameters:
Python values to bind to placeholders in *sql*.
A :class:`!dict` if named placeholders are used.
A :term:`!sequence` if unnamed placeholders are used.
See :ref:`sqlite3-placeholders`.
:type parameters: :class:`dict` | :term:`sequence`
:raises ProgrammingError:
When *sql* contains more than one SQL statement.
When :ref:`named placeholders <sqlite3-placeholders>` are used
and *parameters* is a sequence instead of a :class:`dict`.
If :attr:`~Connection.autocommit` is
:data:`LEGACY_TRANSACTION_CONTROL`,
:attr:`~Connection.isolation_level` is not ``None``,
*sql* is an ``INSERT``, ``UPDATE``, ``DELETE``, or ``REPLACE`` statement,
and there is no open transaction,
a transaction is implicitly opened before executing *sql*.
.. versionchanged:: 3.14
:exc:`ProgrammingError` is emitted if
:ref:`named placeholders <sqlite3-placeholders>` are used
and *parameters* is a sequence instead of a :class:`dict`.
Use :meth:`executescript` to execute multiple SQL statements.
.. method:: executemany(sql, parameters, /)
For every item in *parameters*,
repeatedly execute the :ref:`parameterized <sqlite3-placeholders>`
:abbr:`DML (Data Manipulation Language)` SQL statement *sql*.
Uses the same implicit transaction handling as :meth:`~Cursor.execute`.
:param str sql:
A single SQL DML statement.
:param parameters:
An :term:`!iterable` of parameters to bind with
the placeholders in *sql*.
See :ref:`sqlite3-placeholders`.
:type parameters: :term:`iterable`
:raises ProgrammingError:
When *sql* contains more than one SQL statement
or is not a DML statement,
When :ref:`named placeholders <sqlite3-placeholders>` are used
and the items in *parameters* are sequences instead of :class:`dict`\s.
Example:
.. testcode:: sqlite3.cursor
rows = [
("row1",),
("row2",),
]
# cur is an sqlite3.Cursor object
cur.executemany("INSERT INTO data VALUES(?)", rows)
.. testcleanup:: sqlite3.cursor
con.close()
.. note::
Any resulting rows are discarded,
including DML statements with `RETURNING clauses`_.
.. _RETURNING clauses: https://www.sqlite.org/lang_returning.html
.. versionchanged:: 3.14
:exc:`ProgrammingError` is emitted if
:ref:`named placeholders <sqlite3-placeholders>` are used
and the items in *parameters* are sequences
instead of :class:`dict`\s.
.. method:: executescript(sql_script, /)
Execute the SQL statements in *sql_script*.
If the :attr:`~Connection.autocommit` is
:data:`LEGACY_TRANSACTION_CONTROL`
and there is a pending transaction,
an implicit ``COMMIT`` statement is executed first.
No other implicit transaction control is performed;
any transaction control must be added to *sql_script*.
*sql_script* must be a :class:`string <str>`.
Example:
.. testcode:: sqlite3.cursor
# cur is an sqlite3.Cursor object
cur.executescript("""
BEGIN;
CREATE TABLE person(firstname, lastname, age);
CREATE TABLE book(title, author, published);
CREATE TABLE publisher(name, address);
COMMIT;
""")
.. method:: fetchone()
If :attr:`~Cursor.row_factory` is ``None``,
return the next row query result set as a :class:`tuple`.
Else, pass it to the row factory and return its result.
Return ``None`` if no more data is available.
.. method:: fetchmany(size=cursor.arraysize)
Return the next set of rows of a query result as a :class:`list`.
Return an empty list if no more rows are available.
The number of rows to fetch per call is specified by the *size* parameter.
If *size* is not given, :attr:`arraysize` determines the number of rows
to be fetched.
If fewer than *size* rows are available,
as many rows as are available are returned.
Note there are performance considerations involved with the *size* parameter.
For optimal performance, it is usually best to use the arraysize attribute.
If the *size* parameter is used, then it is best for it to retain the same
value from one :meth:`fetchmany` call to the next.
.. versionchanged:: 3.15
Negative *size* values are rejected by raising :exc:`ValueError`.
.. method:: fetchall()
Return all (remaining) rows of a query result as a :class:`list`.
Return an empty list if no rows are available.
Note that the :attr:`arraysize` attribute can affect the performance of
this operation.
.. method:: close()
Close the cursor now (rather than whenever ``__del__`` is called).
The cursor will be unusable from this point forward; a :exc:`ProgrammingError`
exception will be raised if any operation is attempted with the cursor.
.. method:: setinputsizes(sizes, /)
Required by the DB-API. Does nothing in :mod:`!sqlite3`.
.. method:: setoutputsize(size, column=None, /)
Required by the DB-API. Does nothing in :mod:`!sqlite3`.
.. attribute:: arraysize
Read/write attribute that controls the number of rows returned by :meth:`fetchmany`.
The default value is 1 which means a single row would be fetched per call.
.. versionchanged:: 3.15
Negative values are rejected by raising :exc:`ValueError`.
.. attribute:: connection
Read-only attribute that provides the SQLite database :class:`Connection`
belonging to the cursor. A :class:`Cursor` object created by
calling :meth:`con.cursor() <Connection.cursor>` will have a
:attr:`connection` attribute that refers to *con*:
.. doctest::
>>> con = sqlite3.connect(":memory:")
>>> cur = con.cursor()
>>> cur.connection == con
True
>>> con.close()
.. attribute:: description
Read-only attribute that provides the column names of the last query. To
remain compatible with the Python DB API, it returns a 7-tuple for each
column where the last six items of each tuple are ``None``.
It is set for ``SELECT`` statements without any matching rows as well.
.. attribute:: lastrowid
Read-only attribute that provides the row id of the last inserted row. It
is only updated after successful ``INSERT`` or ``REPLACE`` statements
using the :meth:`execute` method. For other statements, after
:meth:`executemany` or :meth:`executescript`, or if the insertion failed,
the value of ``lastrowid`` is left unchanged. The initial value of
``lastrowid`` is ``None``.
.. note::
Inserts into ``WITHOUT ROWID`` tables are not recorded.
.. versionchanged:: 3.6
Added support for the ``REPLACE`` statement.
.. attribute:: rowcount
Read-only attribute that provides the number of modified rows for
``INSERT``, ``UPDATE``, ``DELETE``, and ``REPLACE`` statements;
is ``-1`` for other statements,
including :abbr:`CTE (Common Table Expression)` queries.
It is only updated by the :meth:`execute` and :meth:`executemany` methods,
after the statement has run to completion.
This means that any resulting rows must be fetched in order for
:attr:`!rowcount` to be updated.
.. attribute:: row_factory
Control how a row fetched from this :class:`!Cursor` is represented.
If ``None``, a row is represented as a :class:`tuple`.
Can be set to the included :class:`sqlite3.Row`;
or a :term:`callable` that accepts two arguments,
a :class:`Cursor` object and the :class:`!tuple` of row values,
and returns a custom object representing an SQLite row.
Defaults to what :attr:`Connection.row_factory` was set to
when the :class:`!Cursor` was created.
Assigning to this attribute does not affect
:attr:`Connection.row_factory` of the parent connection.
See :ref:`sqlite3-howto-row-factory` for more details.
.. The sqlite3.Row example used to be a how-to. It has now been incorporated into the Row reference. We keep the anchor here in order not to break existing links.
.. _sqlite3-columns-by-name: .. _sqlite3-row-objects:
Row objects ^^^^^^^^^^^
.. class:: Row
A :class:!Row instance serves as a highly optimized
:attr:~Connection.row_factory for :class:Connection objects.
It supports iteration, equality testing, :func:len,
and :term:mapping access by column name and index.
Two :class:!Row objects compare equal
if they have identical column names and values.
See :ref:sqlite3-howto-row-factory for more details.
.. method:: keys
Return a :class:`list` of column names as :class:`strings <str>`.
Immediately after a query,
it is the first member of each tuple in :attr:`Cursor.description`.
.. versionchanged:: 3.5 Added support of slicing.
.. _sqlite3-blob-objects:
Blob objects ^^^^^^^^^^^^
.. class:: Blob
.. versionadded:: 3.11
A :class:Blob instance is a :term:file-like object
that can read and write data in an SQLite :abbr:BLOB (Binary Large OBject).
Call :func:len(blob) <len> to get the size (number of bytes) of the blob.
Use indices and :term:slices <slice> for direct access to the blob data.
Use the :class:Blob as a :term:context manager to ensure that the blob
handle is closed after use.
.. testcode::
con = sqlite3.connect(":memory:")
con.execute("CREATE TABLE test(blob_col blob)")
con.execute("INSERT INTO test(blob_col) VALUES(zeroblob(13))")
# Write to our blob, using two write operations:
with con.blobopen("test", "blob_col", 1) as blob:
blob.write(b"hello, ")
blob.write(b"world.")
# Modify the first and last bytes of our blob
blob[0] = ord("H")
blob[-1] = ord("!")
# Read the contents of our blob
with con.blobopen("test", "blob_col", 1) as blob:
greeting = blob.read()
print(greeting) # outputs "b'Hello, world!'"
con.close()
.. testoutput:: :hide:
b'Hello, world!'
.. method:: close()
Close the blob.
The blob will be unusable from this point onward. An
:class:`~sqlite3.Error` (or subclass) exception will be raised if any
further operation is attempted with the blob.
.. method:: read(length=-1, /)
Read *length* bytes of data from the blob at the current offset position.
If the end of the blob is reached, the data up to
:abbr:`EOF (End of File)` will be returned. When *length* is not
specified, or is negative, :meth:`~Blob.read` will read until the end of
the blob.
.. method:: write(data, /)
Write *data* to the blob at the current offset. This function cannot
change the blob length. Writing beyond the end of the blob will raise
:exc:`ValueError`.
.. method:: tell()
Return the current access position of the blob.
.. method:: seek(offset, origin=os.SEEK_SET, /)
Set the current access position of the blob to *offset*. The *origin*
argument defaults to :const:`os.SEEK_SET` (absolute blob positioning).
Other values for *origin* are :const:`os.SEEK_CUR` (seek relative to the
current position) and :const:`os.SEEK_END` (seek relative to the blob’s
end).
PrepareProtocol objects ^^^^^^^^^^^^^^^^^^^^^^^
.. class:: PrepareProtocol
The PrepareProtocol type's single purpose is to act as a :pep:246 style
adaption protocol for objects that can :ref:adapt themselves <sqlite3-conform> to :ref:native SQLite types <sqlite3-types>.
.. _sqlite3-exceptions:
Exceptions ^^^^^^^^^^
The exception hierarchy is defined by the DB-API 2.0 (:pep:249).
.. exception:: Warning
This exception is not currently raised by the :mod:!sqlite3 module,
but may be raised by applications using :mod:!sqlite3,
for example if a user-defined function truncates data while inserting.
Warning is a subclass of :exc:Exception.
.. exception:: Error
The base class of the other exceptions in this module.
Use this to catch all errors with one single :keyword:except statement.
Error is a subclass of :exc:Exception.
If the exception originated from within the SQLite library, the following two attributes are added to the exception:
.. attribute:: sqlite_errorcode
The numeric error code from the
`SQLite API <https://sqlite.org/rescode.html>`_
.. versionadded:: 3.11
.. attribute:: sqlite_errorname
The symbolic name of the numeric error code
from the `SQLite API <https://sqlite.org/rescode.html>`_
.. versionadded:: 3.11
.. exception:: InterfaceError
Exception raised for misuse of the low-level SQLite C API.
In other words, if this exception is raised, it probably indicates a bug in the
:mod:!sqlite3 module.
InterfaceError is a subclass of :exc:Error.
.. exception:: DatabaseError
Exception raised for errors that are related to the database.
This serves as the base exception for several types of database errors.
It is only raised implicitly through the specialised subclasses.
DatabaseError is a subclass of :exc:Error.
.. exception:: DataError
Exception raised for errors caused by problems with the processed data,
like numeric values out of range, and strings which are too long.
DataError is a subclass of :exc:DatabaseError.
.. exception:: OperationalError
Exception raised for errors that are related to the database's operation,
and not necessarily under the control of the programmer.
For example, the database path is not found,
or a transaction could not be processed.
OperationalError is a subclass of :exc:DatabaseError.
.. exception:: IntegrityError
Exception raised when the relational integrity of the database is affected,
e.g. a foreign key check fails. It is a subclass of :exc:DatabaseError.
.. exception:: InternalError
Exception raised when SQLite encounters an internal error.
If this is raised, it may indicate that there is a problem with the runtime
SQLite library.
InternalError is a subclass of :exc:DatabaseError.
.. exception:: ProgrammingError
Exception raised for :mod:!sqlite3 API programming errors,
for example supplying the wrong number of bindings to a query,
or trying to operate on a closed :class:Connection.
ProgrammingError is a subclass of :exc:DatabaseError.
.. exception:: NotSupportedError
Exception raised in case a method or database API is not supported by the
underlying SQLite library. For example, setting deterministic to
True in :meth:~Connection.create_function, if the underlying SQLite library
does not support deterministic functions.
NotSupportedError is a subclass of :exc:DatabaseError.
.. _sqlite3-types:
SQLite and Python types ^^^^^^^^^^^^^^^^^^^^^^^
SQLite natively supports the following types: NULL, INTEGER,
REAL, TEXT, BLOB.
The following Python types can thus be sent to SQLite without any problem:
+-------------------------------+-------------+
| Python type | SQLite type |
+===============================+=============+
| None | NULL |
+-------------------------------+-------------+
| :class:int | INTEGER |
+-------------------------------+-------------+
| :class:float | REAL |
+-------------------------------+-------------+
| :class:str | TEXT |
+-------------------------------+-------------+
| :class:bytes | BLOB |
+-------------------------------+-------------+
This is how SQLite types are converted to Python types by default:
+-------------+----------------------------------------------+
| SQLite type | Python type |
+=============+==============================================+
| NULL | None |
+-------------+----------------------------------------------+
| INTEGER | :class:int |
+-------------+----------------------------------------------+
| REAL | :class:float |
+-------------+----------------------------------------------+
| TEXT | depends on :attr:~Connection.text_factory, |
| | :class:str by default |
+-------------+----------------------------------------------+
| BLOB | :class:bytes |
+-------------+----------------------------------------------+
The type system of the :mod:!sqlite3 module is extensible in two ways: you can
store additional Python types in an SQLite database via
:ref:object adapters <sqlite3-adapters>,
and you can let the :mod:!sqlite3 module convert SQLite types to
Python types via :ref:converters <sqlite3-converters>.
.. _sqlite3-default-converters:
Default adapters and converters (deprecated) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. note::
The default adapters and converters are deprecated as of Python 3.12.
Instead, use the :ref:sqlite3-adapter-converter-recipes
and tailor them to your needs.
The deprecated default adapters and converters consist of:
datetime.date objects to :class:strings <str> in
ISO 8601_ format.datetime.datetime objects to strings in
ISO 8601 format.declared <sqlite3-converters> "date" types to
:class:datetime.date objects.datetime.datetime objects.
Fractional parts will be truncated to 6 digits (microsecond precision)... note::
The default "timestamp" converter ignores UTC offsets in the database and
always returns a naive :class:datetime.datetime object. To preserve UTC
offsets in timestamps, either leave converters disabled, or register an
offset-aware converter with :func:register_converter.
.. deprecated:: 3.12
.. _ISO 8601: https://en.wikipedia.org/wiki/ISO_8601
.. _sqlite3-cli:
Command-line interface ^^^^^^^^^^^^^^^^^^^^^^
The :mod:!sqlite3 module can be invoked as a script,
using the interpreter's :option:-m switch,
in order to provide a simple SQLite shell.
The argument signature is as follows::
python -m sqlite3 [-h] [-v] [filename] [sql]
Type .quit or CTRL-D to exit the shell.
.. program:: python -m sqlite3 [-h] [-v] [filename] [sql]
.. option:: -h, --help
Print CLI help.
.. option:: -v, --version
Print underlying SQLite library version.
.. versionadded:: 3.12
.. _sqlite3-howtos:
.. _sqlite3-placeholders:
How to use placeholders to bind values in SQL queries ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
SQL operations usually need to use values from Python variables. However,
beware of using Python's string operations to assemble queries, as they
are vulnerable to SQL injection attacks_. For example, an attacker can simply
close the single quote and inject OR TRUE to select all rows::
Never do this -- insecure!
symbol = input() ' OR TRUE; -- sql = "SELECT * FROM stocks WHERE symbol = '%s'" % symbol print(sql) SELECT * FROM stocks WHERE symbol = '' OR TRUE; --' cur.execute(sql)
Instead, use the DB-API's parameter substitution. To insert a variable into a
query string, use a placeholder in the string, and substitute the actual values
into the query by providing them as a :class:tuple of values to the second
argument of the cursor's :meth:~Cursor.execute method.
An SQL statement may use one of two kinds of placeholders:
question marks (qmark style) or named placeholders (named style).
For the qmark style, parameters must be a
:term:sequence whose length must match the number of placeholders,
or a :exc:ProgrammingError is raised.
For the named style, parameters must be
an instance of a :class:dict (or a subclass),
which must contain keys for all named parameters;
any extra items are ignored.
Here's an example of both styles:
.. testcode::
con = sqlite3.connect(":memory:") cur = con.execute("CREATE TABLE lang(name, first_appeared)")
data = ( {"name": "C", "year": 1972}, {"name": "Fortran", "year": 1957}, {"name": "Python", "year": 1991}, {"name": "Go", "year": 2009}, ) cur.executemany("INSERT INTO lang VALUES(:name, :year)", data)
params = (1972,) cur.execute("SELECT * FROM lang WHERE first_appeared = ?", params) print(cur.fetchall()) con.close()
.. testoutput:: :hide:
[('C', 1972)]
.. note::
:pep:249 numeric placeholders are not supported.
If used, they will be interpreted as named placeholders.
.. _sqlite3-adapters:
How to adapt custom Python types to SQLite values ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
SQLite supports only a limited set of data types natively.
To store custom Python types in SQLite databases, adapt them to one of the
:ref:Python types SQLite natively understands <sqlite3-types>.
There are two ways to adapt Python objects to SQLite types: letting your object adapt itself, or using an adapter callable. The latter will take precedence above the former. For a library that exports a custom type, it may make sense to enable that type to adapt itself. As an application developer, it may make more sense to take direct control by registering custom adapter functions.
.. _sqlite3-conform:
How to write adaptable objects """"""""""""""""""""""""""""""
Suppose we have a :class:!Point class that represents a pair of coordinates,
x and y, in a Cartesian coordinate system.
The coordinate pair will be stored as a text string in the database,
using a semicolon to separate the coordinates.
This can be implemented by adding a __conform__(self, protocol)
method which returns the adapted value.
The object passed to protocol will be of type :class:PrepareProtocol.
.. testcode::
class Point: def init(self, x, y): self.x, self.y = x, y
def __conform__(self, protocol):
if protocol is sqlite3.PrepareProtocol:
return f"{self.x};{self.y}"
con = sqlite3.connect(":memory:") cur = con.cursor()
cur.execute("SELECT ?", (Point(4.0, -3.2),)) print(cur.fetchone()[0]) con.close()
.. testoutput:: :hide:
4.0;-3.2
How to register adapter callables """""""""""""""""""""""""""""""""
The other possibility is to create a function that converts the Python object
to an SQLite-compatible type.
This function can then be registered using :func:register_adapter.
.. testcode::
class Point: def init(self, x, y): self.x, self.y = x, y
def adapt_point(point): return f"{point.x};{point.y}"
sqlite3.register_adapter(Point, adapt_point)
con = sqlite3.connect(":memory:") cur = con.cursor()
cur.execute("SELECT ?", (Point(1.0, 2.5),)) print(cur.fetchone()[0]) con.close()
.. testoutput:: :hide:
1.0;2.5
.. _sqlite3-converters:
How to convert SQLite values to custom Python types ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Writing an adapter lets you convert from custom Python types to SQLite values. To be able to convert from SQLite values to custom Python types, we use converters.
Let's go back to the :class:!Point class. We stored the x and y coordinates
separated via semicolons as strings in SQLite.
First, we'll define a converter function that accepts the string as a parameter
and constructs a :class:!Point object from it.
.. note::
Converter functions are always passed a :class:bytes object,
no matter the underlying SQLite data type.
.. testcode::
def convert_point(s): x, y = map(float, s.split(b";")) return Point(x, y)
We now need to tell :mod:!sqlite3 when it should convert a given SQLite value.
This is done when connecting to a database, using the detect_types parameter
of :func:connect. There are three options:
PARSE_DECLTYPESPARSE_COLNAMESsqlite3.PARSE_DECLTYPES | sqlite3.PARSE_COLNAMES.
Column names take precedence over declared types.The following example illustrates the implicit and explicit approaches:
.. testcode::
class Point: def init(self, x, y): self.x, self.y = x, y
def __repr__(self):
return f"Point({self.x}, {self.y})"
def adapt_point(point): return f"{point.x};{point.y}"
def convert_point(s): x, y = list(map(float, s.split(b";"))) return Point(x, y)
sqlite3.register_adapter(Point, adapt_point) sqlite3.register_converter("point", convert_point)
p = Point(4.0, -3.2) con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES) cur = con.execute("CREATE TABLE test(p point)")
cur.execute("INSERT INTO test(p) VALUES(?)", (p,)) cur.execute("SELECT p FROM test") print("with declared types:", cur.fetchone()[0]) cur.close() con.close()
con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_COLNAMES) cur = con.execute("CREATE TABLE test(p)")
cur.execute("INSERT INTO test(p) VALUES(?)", (p,)) cur.execute('SELECT p AS "p [point]" FROM test') print("with column names:", cur.fetchone()[0]) cur.close() con.close()
.. testoutput:: :hide:
with declared types: Point(4.0, -3.2) with column names: Point(4.0, -3.2)
.. _sqlite3-adapter-converter-recipes:
Adapter and converter recipes ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This section shows recipes for common adapters and converters.
.. testcode::
import datetime as dt import sqlite3
def adapt_date_iso(val): """Adapt datetime.date to ISO 8601 date.""" return val.isoformat()
def adapt_datetime_iso(val): """Adapt datetime.datetime to timezone-naive ISO 8601 date.""" return val.replace(tzinfo=None).isoformat()
def adapt_datetime_epoch(val): """Adapt datetime.datetime to Unix timestamp.""" return int(val.timestamp())
sqlite3.register_adapter(dt.date, adapt_date_iso) sqlite3.register_adapter(dt.datetime, adapt_datetime_iso) sqlite3.register_adapter(dt.datetime, adapt_datetime_epoch)
def convert_date(val): """Convert ISO 8601 date to datetime.date object.""" return dt.date.fromisoformat(val.decode())
def convert_datetime(val): """Convert ISO 8601 datetime to datetime.datetime object.""" return dt.datetime.fromisoformat(val.decode())
def convert_timestamp(val): """Convert Unix epoch timestamp to datetime.datetime object.""" return dt.datetime.fromtimestamp(int(val))
sqlite3.register_converter("date", convert_date) sqlite3.register_converter("datetime", convert_datetime) sqlite3.register_converter("timestamp", convert_timestamp)
.. testcode:: :hide:
when = dt.datetime(2019, 5, 18, 15, 17, 8, 123456)
assert adapt_date_iso(when.date()) == "2019-05-18" assert convert_date(b"2019-05-18") == when.date()
assert adapt_datetime_iso(when) == "2019-05-18T15:17:08.123456" assert convert_datetime(b"2019-05-18T15:17:08.123456") == when
now = dt.datetime.now().replace(microsecond=0) current_timestamp = int(now.timestamp())
assert adapt_datetime_epoch(now) == current_timestamp assert convert_timestamp(str(current_timestamp).encode()) == now
.. _sqlite3-connection-shortcuts:
How to use connection shortcut methods ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Using the :meth:~Connection.execute,
:meth:~Connection.executemany, and :meth:~Connection.executescript
methods of the :class:Connection class, your code can
be written more concisely because you don't have to create the (often
superfluous) :class:Cursor objects explicitly. Instead, the :class:Cursor
objects are created implicitly and these shortcut methods return the cursor
objects. This way, you can execute a SELECT statement and iterate over it
directly using only a single call on the :class:Connection object.
.. testcode::
con = sqlite3.connect(":memory:") con.execute("CREATE TABLE lang(name, first_appeared)") data = [ ("C++", 1985), ("Objective-C", 1984), ] con.executemany("INSERT INTO lang(name, first_appeared) VALUES(?, ?)", data)
for row in con.execute("SELECT name, first_appeared FROM lang"): print(row)
print("I just deleted", con.execute("DELETE FROM lang").rowcount, "rows")
con.close()
.. testoutput:: :hide:
('C++', 1985) ('Objective-C', 1984) I just deleted 2 rows
.. _sqlite3-connection-context-manager:
How to use the connection context manager ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
A :class:Connection object can be used as a context manager that
automatically commits or rolls back open transactions when leaving the body of
the context manager.
If the body of the :keyword:with statement finishes without exceptions,
the transaction is committed.
If this commit fails,
or if the body of the with statement raises an uncaught exception,
the transaction is rolled back.
If :attr:~Connection.autocommit is False,
a new transaction is implicitly opened after committing or rolling back.
If there is no open transaction upon leaving the body of the with statement,
or if :attr:~Connection.autocommit is True,
the context manager does nothing.
.. note::
The context manager neither implicitly opens a new transaction
nor closes the connection. If you need a closing context manager, consider
using :meth:contextlib.closing.
.. testcode::
con = sqlite3.connect(":memory:") con.execute("CREATE TABLE lang(id INTEGER PRIMARY KEY, name VARCHAR UNIQUE)")
with con: con.execute("INSERT INTO lang(name) VALUES(?)", ("Python",))
try: with con: con.execute("INSERT INTO lang(name) VALUES(?)", ("Python",)) except sqlite3.IntegrityError: print("couldn't add Python twice")
con.close()
.. testoutput:: :hide:
couldn't add Python twice
.. _sqlite3-uri-tricks:
How to work with SQLite URIs ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Some useful URI tricks include:
.. doctest::
con = sqlite3.connect("file:tutorial.db?mode=ro", uri=True) con.execute("CREATE TABLE readonly(data)") Traceback (most recent call last): OperationalError: attempt to write a readonly database con.close()
~sqlite3.OperationalError if unable to create a new file:.. doctest::
con = sqlite3.connect("file:nosuchdb.db?mode=rw", uri=True) Traceback (most recent call last): OperationalError: unable to open database file
.. testcode::
db = "file:mem1?mode=memory&cache=shared" con1 = sqlite3.connect(db, uri=True) con2 = sqlite3.connect(db, uri=True) with con1: con1.execute("CREATE TABLE shared(data)") con1.execute("INSERT INTO shared VALUES(28)") res = con2.execute("SELECT data FROM shared") assert res.fetchone() == (28,)
con1.close() con2.close()
More information about this feature, including a list of parameters,
can be found in the SQLite URI documentation_.
.. _SQLite URI documentation: https://www.sqlite.org/uri.html
.. _sqlite3-howto-row-factory:
How to create and use row factories ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
By default, :mod:!sqlite3 represents each row as a :class:tuple.
If a :class:!tuple does not suit your needs,
you can use the :class:sqlite3.Row class
or a custom :attr:~Cursor.row_factory.
While :attr:!row_factory exists as an attribute both on the
:class:Cursor and the :class:Connection,
it is recommended to set :class:Connection.row_factory,
so all cursors created from the connection will use the same row factory.
:class:!Row provides indexed and case-insensitive named access to columns,
with minimal memory overhead and performance impact over a :class:!tuple.
To use :class:!Row as a row factory,
assign it to the :attr:!row_factory attribute:
.. doctest::
con = sqlite3.connect(":memory:") con.row_factory = sqlite3.Row
Queries now return :class:!Row objects:
.. doctest::
res = con.execute("SELECT 'Earth' AS name, 6378 AS radius") row = res.fetchone() row.keys() ['name', 'radius'] row[0] # Access by index. 'Earth' row["name"] # Access by name. 'Earth' row["RADIUS"] # Column names are case-insensitive. 6378 con.close()
.. note::
The ``FROM`` clause can be omitted in the ``SELECT`` statement, as in the
above example. In such cases, SQLite returns a single row with columns
defined by expressions, e.g. literals, with the given aliases
``expr AS alias``.
You can create a custom :attr:~Cursor.row_factory
that returns each row as a :class:dict, with column names mapped to values:
.. testcode::
def dict_factory(cursor, row): fields = [column[0] for column in cursor.description] return {key: value for key, value in zip(fields, row)}
Using it, queries now return a :class:!dict instead of a :class:!tuple:
.. doctest::
con = sqlite3.connect(":memory:") con.row_factory = dict_factory for row in con.execute("SELECT 1 AS a, 2 AS b"): ... print(row) {'a': 1, 'b': 2} con.close()
The following row factory returns a :term:named tuple:
.. testcode::
from collections import namedtuple
def namedtuple_factory(cursor, row): fields = [column[0] for column in cursor.description] cls = namedtuple("Row", fields) return cls._make(row)
:func:!namedtuple_factory can be used as follows:
.. doctest::
con = sqlite3.connect(":memory:") con.row_factory = namedtuple_factory cur = con.execute("SELECT 1 AS a, 2 AS b") row = cur.fetchone() row Row(a=1, b=2) row[0] # Indexed access. 1 row.b # Attribute access. 2 con.close()
With some adjustments, the above recipe can be adapted to use a
:class:~dataclasses.dataclass, or any other custom class,
instead of a :class:~collections.namedtuple.
.. _sqlite3-howto-encoding:
How to handle non-UTF-8 text encodings ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
By default, :mod:!sqlite3 uses :class:str to adapt SQLite values
with the TEXT data type.
This works well for UTF-8 encoded text, but it might fail for other encodings
and invalid UTF-8.
You can use a custom :attr:~Connection.text_factory to handle such cases.
Because of SQLite's flexible typing_, it is not uncommon to encounter table
columns with the TEXT data type containing non-UTF-8 encodings,
or even arbitrary data.
To demonstrate, let's assume we have a database with ISO-8859-2 (Latin-2)
encoded text, for example a table of Czech-English dictionary entries.
Assuming we now have a :class:Connection instance :py:data:!con
connected to this database,
we can decode the Latin-2 encoded text using this :attr:~Connection.text_factory:
.. testcode::
con.text_factory = lambda data: str(data, encoding="latin2")
For invalid UTF-8 or arbitrary data in stored in TEXT table columns,
you can use the following technique, borrowed from the :ref:unicode-howto:
.. testcode::
con.text_factory = lambda data: str(data, errors="surrogateescape")
.. note::
The :mod:!sqlite3 module API does not support strings
containing surrogates.
.. seealso::
:ref:unicode-howto
.. _sqlite3-explanation:
.. _sqlite3-transaction-control: .. _sqlite3-controlling-transactions:
Transaction control ^^^^^^^^^^^^^^^^^^^
:mod:!sqlite3 offers multiple methods of controlling whether,
when and how database transactions are opened and closed.
:ref:sqlite3-transaction-control-autocommit is recommended,
while :ref:sqlite3-transaction-control-isolation-level
retains the pre-Python 3.12 behaviour.
.. _sqlite3-transaction-control-autocommit:
Transaction control via the autocommit attribute
""""""""""""""""""""""""""""""""""""""""""""""""""""
The recommended way of controlling transaction behaviour is through
the :attr:Connection.autocommit attribute,
which should preferably be set using the autocommit parameter
of :func:connect.
It is suggested to set autocommit to False,
which implies :pep:249-compliant transaction control.
This means:
!sqlite3 ensures that a transaction is always open,
so :func:connect, :meth:Connection.commit, and :meth:Connection.rollback
will implicitly open a new transaction
(immediately after closing the pending one, for the latter two).
:mod:!sqlite3 uses BEGIN DEFERRED statements when opening transactions.!commit.!rollback.~Connection.close-ed with pending changes.Set autocommit to True to enable SQLite's autocommit mode_.
In this mode, :meth:Connection.commit and :meth:Connection.rollback
have no effect.
Note that SQLite's autocommit mode is distinct from
the :pep:249-compliant :attr:Connection.autocommit attribute;
use :attr:Connection.in_transaction to query
the low-level SQLite autocommit mode.
Set autocommit to :data:LEGACY_TRANSACTION_CONTROL
to leave transaction control behaviour to the
:attr:Connection.isolation_level attribute.
See :ref:sqlite3-transaction-control-isolation-level for more information.
.. _sqlite3-transaction-control-isolation-level:
Transaction control via the isolation_level attribute
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.. note::
The recommended way of controlling transactions is via the
:attr:~Connection.autocommit attribute.
See :ref:sqlite3-transaction-control-autocommit.
If :attr:Connection.autocommit is set to
:data:LEGACY_TRANSACTION_CONTROL (the default),
transaction behaviour is controlled using
the :attr:Connection.isolation_level attribute.
Otherwise, :attr:!isolation_level has no effect.
If the connection attribute :attr:~Connection.isolation_level
is not None,
new transactions are implicitly opened before
:meth:~Cursor.execute and :meth:~Cursor.executemany executes
INSERT, UPDATE, DELETE, or REPLACE statements;
for other statements, no implicit transaction handling is performed.
Use the :meth:~Connection.commit and :meth:~Connection.rollback methods
to respectively commit and roll back pending transactions.
You can choose the underlying SQLite transaction behaviour_ —
that is, whether and what type of BEGIN statements :mod:!sqlite3
implicitly executes –
via the :attr:~Connection.isolation_level attribute.
If :attr:~Connection.isolation_level is set to None,
no transactions are implicitly opened at all.
This leaves the underlying SQLite library in autocommit mode_,
but also allows the user to perform their own transaction handling
using explicit SQL statements.
The underlying SQLite library autocommit mode can be queried using the
:attr:~Connection.in_transaction attribute.
The :meth:~Cursor.executescript method implicitly commits
any pending transaction before execution of the given SQL script,
regardless of the value of :attr:~Connection.isolation_level.
.. versionchanged:: 3.6
:mod:!sqlite3 used to implicitly commit an open transaction before DDL
statements. This is no longer the case.
.. versionchanged:: 3.12
The recommended way of controlling transactions is now via the
:attr:~Connection.autocommit attribute.
.. _autocommit mode: https://www.sqlite.org/lang_transaction.html#implicit_versus_explicit_transactions
.. _SQLite transaction behaviour: https://www.sqlite.org/lang_transaction.html#deferred_immediate_and_exclusive_transactions
.. testcleanup::
import os os.remove("backup.db") os.remove("dump.sql") os.remove("example.db") os.remove("tutorial.db")