trigger on update of a particular column
-- SQL Server (update my_table after update on my_table)
CREATE TRIGGER trigger_name ON my_table AFTER UPDATE AS
IF UPDATE (col_name) -- Optional, for particular column
BEGIN
UPDATE my_table SET my_col_date = getdate() FROM my_table
END;
-- Oracle (insert into log table after update on my_table)
CREATE OR REPLACE TRIGGER trigger_name AFTER UPDATE ON my_table
FOR EACH ROW
BEGIN
INSERT INTO my_log_table (LOG_DATE, ACTION) VALUES (SYSDATE, 'Changed');
END;