MySQL INSERT on condition

Question

I have a table user_has_alerts (userID, alertID, dateAlerted) and i'm trying to update all NULL values in dateAlerted field for a given user to the current date. Any help would be much appreciated.

Answer 1

UPDATE user_has_alerts SET dateAlerted = CURDATE() 
 WHERE userID = X AND dateAlerted IS NULL

Answer 2

UPDATE `user_has_alerts` SET `dateAlerted` = NOW() WHERE `dateAlerted` IS NULL AND userID = 1