presto-docs/src/main/sphinx/sql/drop-function.rst
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DROP [TEMPORARY] FUNCTION [ IF EXISTS ] qualified_function_name [ ( parameter_type[, ...] ) ]
Drop existing functions that matches the given function name.
The optional parameter type list can be specified to narrow down the match to a specific function signature.
The optional IF EXISTS clause causes the NOT_FOUND error
to be suppressed if no matching function signature exists.
When TEMPORARY is specified, temporary functions with matching
criteria are dropped.
Drop the function example.default.tan(double)::
DROP FUNCTION example.default.tan(double)
If only one function exists for example.default.tan, parameter type list may be omitted::
DROP FUNCTION example.default.tan
Drop the function example.default.tan(double) if it exists::
DROP FUNCTION IF EXISTS example.default.tan(double)
:doc:create-function, :doc:alter-function, :doc:show-functions