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+--- Thread: How to handle MySQL CONSTRAINT / error number (/showthread.php?tid=36994)
How to handle MySQL CONSTRAINT / error number - El Forum - 12-22-2010
[eluser]Unknown[/eluser]
Hello CodeIgniter community,
I have an problem handling MySQL CONSTRAINT error.
For obvious reason, I can not delete record in MySQL table because another records in other table reference it.
Quote:A Database Error Occurred
Error Number: 1451
Cannot delete or update a parent row: a foreign key constraint fails (`treg`.`participant`, CONSTRAINT `fk_participant_seminar` FOREIGN KEY (`seminar_seminar_id`) REFERENCES `seminar` (`seminar_id`) ON DELETE NO ACTION ON UPDATE NO ACTION)
DELETE FROM `seminar` WHERE `seminar_id` = '31'
I need to know when this error is occurred to display appropriate error text to user.
Also I would like to have MySQL error number from last query.
How to handle this issue?
How to handle MySQL CONSTRAINT / error number - El Forum - 12-22-2010
[eluser]sooner[/eluser]
check the php documentation for the mysql functions.
You can use mysql_errno() to find the numerical value of the error message and mysql_error() returns the text of the error message.
if you are using mysqli then mysqli->error and mysqli->errno
I hope it helps you.
How to handle MySQL CONSTRAINT / error number - El Forum - 12-22-2010
[eluser]techgnome[/eluser]
How about using some offensive programming rather than some defensive programming? CHECK the child table FIRST... THEN delete. I you know this can happen, PLAN for it. Deal with it. Go on the offensive. Be proactive. Error handling should be for the "Ooops, I didn't count on that." situations.
Or, if your database supports it, create a foreign key relationship with a CASCADE DELETE so that when you delete the Parent, the Child records will go with it. (if that's appropriate).
-tg
How to handle MySQL CONSTRAINT / error number - El Forum - 12-24-2010
[eluser]Unknown[/eluser]
RE: techgnome
You are right.
I have re-organise the code and use db transactions to fitful my needs.
Anyway, I need sometimes to handle MySQL error (for example, handling duplicated username insert) and those two function do the job:
Code:
$errtxt = $this->db->_error_message();
$errno = $this->db->_error_number();Thank You all for support.