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Re: Trigger for read-only column
Posted by: Peter Brawley
Date: June 15, 2013 09:46AM

Without a Handler, SIGNAL under a SqlState error condition stops execution. Try the null-safe operator and define a warning SqlState instead ...

drop table if exists t;
create table t(id int, j int);
delimiter go
create trigger tidlock before update on t for each row 
  set @monitor='Starting';
  if !( <=> then 
    signal sqlstate '01999' set message_text = 'ID may not be updated.'; 
    set new.ID=old.ID;
  end if; 
  set @monitor='Continuing';
delimiter ;
insert into t values(null,1);
update t set id=2,j=2 where id is null;
select id, j, @monitor from t;
| id   | j    | @monitor   |
| NULL |    2 | Continuing |

Edited 1 time(s). Last edit at 06/15/2013 12:32PM by Peter Brawley.

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Written By
June 12, 2013 09:25AM
Re: Trigger for read-only column
June 15, 2013 09:46AM

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