mysql trigger on update with insert statement

Question

I am trying to create a simple trigger which is handled on update operations. The trigger is checking before update if a record of an update exists, then if not it is created.

DELIMITER ;;
CREATE TRIGGER trig
BEFORE UPDATE ON table
FOR EACH ROW
BEGIN
IF old is null then
INSERT INTO table(table.col1, table.col2) VALUES ('new.table.col1','new.table.col2');
END IF;
END;
;;
DELIMITER ;

Why is it not adding a record if update is trying to update some non existing record?

Answer 1

I think that you don't need a trigger at all and - based on your comments - you want an INSERT ... ON DUPLICATE KEY UPDATE. If there is a UNIQUE constraint on (col2), this will work:

INSERT INTO table_name
  (col1, col2) 
VALUES 
  (@col1, @col2)                  -- the new values here
ON DUPLICATE KEY UPDATE
  col1 = col1 + VALUES(col1) ;    -- update the old value by adding the new one

Answer 2

I think what you are looking for is REPLACE.

Try this:

REPLACE INTO table(table.col1, table.col2) VALUES (value1, value2);

No need for a trigger at all.