MySQL Trigger On UPDATE "Unknown Column" Error
Get rid of UNIX_TIMESTAMP() everywhere.  DATETIME fields can be compared directly.

Once you have done that, you will probably notice the missing @ that is causing the error.

I think it can be simplified down to only:

CREATE TRIGGER ...
IF COALESCE(OLD.updateDate, OLD.insertDate) &lt; CURRENT_DATE() - interval 3 month
    INSERT INTO three_month_ago_dad_records SELECT OLD.*;
END IF;
END;