A function can be created or replaced using the same syntax except for the keywords CREATE and REPLACE.
If you specify CREATE, the function must not exist.
If you specify REPLACE, you can either create a new function or replace an existing function with the following restriction: if the function to be replaced was originally created with a specific function name, then that specific function name must be used for the REPLACE FUNCTION statement.
When you replace an existing function, the replaced function does not retain the EXECUTE NOT PROTECTED attribute if one had previously been set using the ALTER FUNCTION statement. See ALTER FUNCTION (External Form).
The advantage to using REPLACE is that you can avoid having to grant the EXECUTE privilege again to all users who already had that privilege on the function.
Refer to the topics below for important restrictions on replacing UDFs that perform UDT-related functionality.
Replacing an Ordering or Transform UDF
- The REPLACE FUNCTION specification must match exactly with the existing method specification in the dictionary.
The function name, parameter list, method entry point name within the EXTERNAL clause, and so on must all match.
- The execution mode for the UDF being replaced must be set to EXECUTE PROTECTED.
If the UDF is currently set to run in the EXECUTE NOT PROTECTED mode, then you must submit an ALTER FUNCTION statement to switch the mode to EXECUTE PROTECTED before you can submit the REPLACE FUNCTION statement. See ALTER FUNCTION (External Form).
Replacing a Casting UDF for a UDT
- DROP CAST
- REPLACE FUNCTION
- CREATE CAST
An attempt to directly replace a casting function using REPLACE FUNCTION results in an error.