docs/control-flow/open-stmt.md
Opens a cursor and executes its query, positioning it before the first row.
The OPEN statement executes the query defined in the cursor declaration, binding any parameter markers if specified. Once opened, the cursor can be used with FETCH to retrieve rows.
OPEN cursor_name [ USING { constant_expr [ AS param_name ] } [, ...] ]
cursor_name
The name of a declared cursor. The cursor can be optionally qualified with a compound statement label to reference a cursor from an outer scope (e.g., outer_label.my_cursor).
USING { constant_expr [ AS param_name ] } [, ...]
Optional clause to bind values to parameter markers in the cursor's query.
constant_expr
A constant expression (literal or variable) to bind to a parameter marker. The expression must be castable to the type expected by the query.
AS param_name
An optional alias for the parameter. For named parameter markers (:param_name), this specifies which parameter to bind. If not specified for positional markers (?), parameters are bound by position.
-- Open a simple cursor without parameters
> BEGIN
DECLARE total INT;
DECLARE my_cursor CURSOR FOR SELECT sum(id) FROM range(10);
OPEN my_cursor;
FETCH my_cursor INTO total;
VALUES (total);
CLOSE my_cursor;
END;
45
-- Open cursor with positional parameters
> BEGIN
DECLARE total INT;
DECLARE param_cursor CURSOR FOR
SELECT sum(id) FROM range(100) WHERE id BETWEEN ? AND ?;
OPEN param_cursor USING 10, 20;
FETCH param_cursor INTO total;
VALUES (total);
CLOSE param_cursor;
END;
165
-- Open cursor with named parameters
> BEGIN
DECLARE min_val INT;
DECLARE named_cursor CURSOR FOR
SELECT min(id) FROM range(100) WHERE id >= :threshold;
OPEN named_cursor USING 25 AS threshold;
FETCH named_cursor INTO min_val;
VALUES (min_val);
CLOSE named_cursor;
END;
25
-- Open cursor using variables as parameters
> BEGIN
DECLARE lower INT DEFAULT 5;
DECLARE upper INT DEFAULT 15;
DECLARE result INT;
DECLARE var_cursor CURSOR FOR
SELECT count(*) FROM range(100) WHERE id BETWEEN ? AND ?;
OPEN var_cursor USING lower, upper;
FETCH var_cursor INTO result;
VALUES (result);
CLOSE var_cursor;
END;
11
-- Open cursor with various data types
> BEGIN
DECLARE type_name STRING;
DECLARE value_sum INT;
DECLARE type_cursor CURSOR FOR
SELECT typeof(:p) as type, sum(:p + id) FROM range(3);
OPEN type_cursor USING 10 AS p;
FETCH type_cursor INTO type_name, value_sum;
VALUES (type_name, value_sum);
CLOSE type_cursor;
END;
INT|33
-- Qualified cursor name with label
> BEGIN
outer_lbl: BEGIN
DECLARE outer_cur CURSOR FOR SELECT max(id) FROM range(10);
DECLARE max_val INT;
OPEN outer_cur;
inner_lbl: BEGIN
DECLARE inner_cur CURSOR FOR SELECT min(id) FROM range(5);
DECLARE min_val INT;
OPEN inner_cur;
FETCH outer_lbl.outer_cur INTO max_val;
FETCH inner_cur INTO min_val;
VALUES (max_val, min_val);
CLOSE inner_cur;
END;
CLOSE outer_cur;
END;
END;
9|0
CURSOR_ALREADY_OPEN error.EXECUTE IMMEDIATE:
?), expressions are bound in the order specified.:name), the AS param_name clause specifies the binding.OPEN time, using current variable values.OPEN time. Subsequent changes to variables or tables do not affect the result set.