DROP FUNCTION name ( [ type [, ...] ] )
The name of an existing function.
The type of function parameters.
Message returned if the command completes successfully.
This message is given if the function specified does not exist in the current database.
DROP FUNCTION will remove references to an existing C function. To execute this command the user must be the owner of the function. The input argument types to the function must be specified, as only the function with the given name and argument types will be removed.
Refer to CREATE FUNCTION for information on creating aggregate functions.
No checks are made to ensure that types, operators or access methods that rely on the function have been removed first.
This command removes the square root function:
DROP FUNCTION sqrt(int4);
DROP FUNCTION is a Postgres language extension.
SQL/PSM is a proposed standard to enable function extensibility. The SQL/PSM DROP FUNCTION statement has the following syntax:
DROP [ SPECIFIC ] FUNCTION name { RESTRICT | CASCADE }