ALTER FUNCTION SQL - Language Statements ALTER FUNCTION change the definition of a function ALTER FUNCTION name ( [ type [, ...] ] ) RENAME TO newname ALTER FUNCTION changes the definition of a function. The only functionality is to rename the function. name The name (optionally schema-qualified) of an existing function. type The data type of an argument of the function. newname The new name of the function. ALTER FUNCTION Message returned if the command was successful. To rename the function sqrt for type integer to square_root: ALTER FUNCTION sqrt(integer) RENAME TO square_root; There is an ALTER FUNCTION statement in the SQL standard, but it does not provide the option to rename the function.