Updatable trigger

(Example in Oracle)

         CREATE OR REPLACE TRIGGER AGENCY_PF.EXAMPLE_TRIGGER
            INSTEAD OF INSERT OR UPDATE OR DELETE ON AGENCY_PF.YOUR_TABLE
            FOR EACH ROW
            DECLARE
            BEGIN
               IF INSERTING THEN
                  NULL;
               ELSIF DELETING THEN
                  NULL;
               ELSIF UPDATING THEN
               -- Update your actual table here
            END ;
         END

(Example in SQL Server)

         CREATE TRIGGER AGENCY_PF.EXAMPLE_TRIGGER ON AGENCY_PF.YOUR_TABLE 
         INSTEAD OF INSERT, UPDATE, DELETE
         AS
         BEGIN
            IF EXISTS(SELECT * FROM DELETED)
            BEGIN
               IF EXISTS(SELECT * FROM INSERTED) 
               BEGIN
               --Update being performed, insert appropriate code here.
               END
               ELSE 
               BEGIN
               --Delete being performed, insert appropriate code here.
               END
            END
            ELSE
            BEGIN
               IF EXISTS(SELECT * FROM INSERTED) 
               BEGIN
               --Insert being performed, insert appropriate code here.
               END 
            END