Question

I have this MySQL table:

create table test.customer (
 ID             INTEGER,
 CREATION_TIME  DATETIME,
 CREATION_USER  VARCHAR(50),
 CHANGE_TIME    TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
 CHANGE_USER    VARCHAR(50),
 PRIMARY KEY(ID)
);

I want to automatically set the user & timestamps for logging purpose. I do have one trigger before insert (actually written only for the creation_time):

delimiter #
create trigger test.customer_creation 
before insert on test.customer 
for each row 
begin
 set NEW.CREATION_TIME = NOW();
 IF (NEW.CREATION_USER is null or NEW.CREATION_USER = '') 
 THEN set NEW.CREATION_USER = USER(); 
 end IF;
end #
delimiter ;

but I don’t really want a trigger just for the CHANGE_USER. Is there a possibility to set the CHANGE_USER with something like: DEFAULT USER()? or do I have to create a additional trigger?

Answer 1

In MySQL you simply can’t use a function as a default value for a column, you can use
the keywords: NULL, CURRENT_TIMESTAMP and localtimestamp, while you can’t use functions(except for now() that is internally represented as a synonym of CURRENT_TIMESTAMP).

So in your case the way to follow is the trigger ON insert … You need the additional trigger .