
Question:
I need a way to check for and pass entries into an audit log for any entries in a table that have been changed. It needs to be abstracted away from the table structure.
For example:
CREATE TRIGGER table1_update BEFORE UPDATE ON table1 FOR EACH ROW BEGIN DECLARE i_column_name varchar(32); DECLARE done INT; DECLARE cursor1 CURSOR FOR SELECT column_name FROM information_schema.columns WHERE table_name = 'table1'; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; OPEN cursor1; REPEAT FETCH cursor1 INTO i_column_name; IF NOT done THEN --pass the variable column_name and its old.i_column_name and new.i_column_name values to the audit table END IF; UNTIL done END REPEAT; CLOSE cursor1; END$$
We have too many tables that need to be audited to custom build every single INSERT, UPDATE, and DELETE trigger. I've tried a number of things and I'm thinking I'm out of luck. Anyone have any ideas?
Solution:1
You can't have an abstract trigger, it must be defined on a specific table. The closest you can get is to put the code for the trigger into a stored procedure, and then the triggers for each table will just call the procedure.
CREATE PROCEDURE audit_update (IN tablename VARCHAR(64)) BEGIN DECLARE i_column_name varchar(32); DECLARE done INT; DECLARE cursor1 CURSOR FOR SELECT column_name FROM information_schema.columns WHERE table_name = tablename; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; OPEN cursor1; REPEAT FETCH cursor1 INTO i_column_name; IF NOT done THEN --pass the variable column_name and its old.i_column_name and new.i_column_name values to the audit table END IF; UNTIL done END REPEAT; CLOSE cursor1; END CREATE TRIGGER table1_update BEFORE UPDATE ON table1 FOR EACH ROW BEGIN CALL audit_update('table1'); END
You should be able to easily script up something that will create the triggers for all of your tables using the information_schema or something along those lines.
SELECT CONCAT('CREATE TRIGGER ', table_name, '_update BEFORE UPDATE ON ', table_name, ...) FROM information_schema...
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