Question

I am trying to set a trigger to record a timestamp in a log table when the main table is updated. I have a main table called cm and have a log table with a timestamp column.

The timestamp column in the log table is set up as follows:

ALTER TABLE log ADD COLUMN modified_timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

The trigger I trying is as follows but throws this error “Error Code 1193. Unknown system variable ‘modified_timestamp’

Trigger:

DELIMITER //
CREATE TRIGGER `ahrq cm`.`table_timestamp` BEFORE UPDATE ON `ahrq    cm`.`ahrq_inventory_all`
FOR EACH ROW begin

set log.modified_timestamp=CURRENT_TIMESTAMP();

end
//

Can anyone shed light on this error?

Answer 1

Your trigger should update the log table using a normal SQL command:

DELIMITER //
CREATE TRIGGER `ahrq cm`.`table_timestamp` BEFORE UPDATE ON `ahrq cm`.`ahrq_inventory_all`
FOR EACH ROW begin

INSERT INTO log (modified_timestamp) VALUES (CURRENT_TIMESTAMP());

end
//