ALTER FUNCTION SQL - Language Statements ALTER FUNCTION change the definition of a function ALTER 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. 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.