Create or replace trigger postgres

Question

I want to \"create or replace\" a trigger for a postgres table. However, there is not such sql expression.

I see that I can do a \"DROP TRIGGER IF EXISTS\"

Answer 1

Postgresql has transaction DDL so BEGIN > DROP > CREATE > COMMIT is the equivalent of CREATE OR REPLACE

This is a nice write-up of how postgre's transactional DDL compares to other systems (such as oracle)

Current postgres planned features regarding triggers do not include adding the REPLACE syntax.

Answer 2

You should use two statements: one for drop trigger and another for creating a trigger.

Example:

DROP TRIGGER IF EXISTS my_trigger
  ON my_schema.my_table;
CREATE TRIGGER my_trigger
  BEFORE INSERT OR UPDATE
  ON my_schema.my_table
  FOR EACH ROW EXECUTE PROCEDURE my_schema.my_function();

Answer 3

you can use below code.

DO $$ BEGIN

CREATE (trigger, type , ...);

EXCEPTION
  WHEN others THEN null;
END $$;

sample:

DO $$ BEGIN

CREATE TRIGGER trigger_workIDExist
  BEFORE INSERT OR UPDATE ON "GalleryModel"
  FOR EACH ROW EXECUTE PROCEDURE check_workIDExist();

EXCEPTION
  WHEN others THEN null;
END $$;

Answer 4

No way to create or replace a trigger but can do this way

DROP TRIGGER IF EXISTS yourtrigger_name on "yourschemaname"."yourtablename";

Answer 5

You can combine CREATE OR REPLACE FUNCTION trigger_function with the following script in your SQL:

DO $$
BEGIN
  IF NOT EXISTS(SELECT *
    FROM information_schema.triggers
    WHERE event_object_table = 'table_name'
    AND trigger_name = 'trigger_name'
  )
  THEN
    CREATE TRIGGER trigger_name AFTER INSERT ON table_name FOR EACH ROW EXECUTE PROCEDURE trigger_function();
  END IF;
END;
$$