Catching MYSQL errors

[HughbertD]

Hi all,

I want to be able to catch a "Cannot delete or update a parent row" error from a mysql database. Instead of just printing the error to the screen, I want to explain that some records need to be altered. Is there a way of doing this?

Thanks for any help

 

[jpadie]

the error will be in the mysql_error() return. you can suppress the default message by prepending an @ to the mysql_query function

$result  = @mysql_query('somequery);
if (!$result){
 switch (mysql_error()){
   case "Cannot delete or update a parent row":
    echo "do something";
    break;
   default:
    echo mysql_error();
 }

it may be easier if you use the error codes rather than the error message.

 

[HughbertD]

I tried something similar to this, like

$error=substr(mysql_error(),0,10)
if ($error == "Cannot upda")
{
echo blah
}

But this did not work either. It just doesn't seem to echo anything onto the screen. I don't think that it is catching anything, does the error code come with mysql_error ?

I'm also unsure how to use break case statements.

Thanks if you can keep helping

 

[jpadie]

personally i don' use foreign key constraints in mysql - i prefer to rely on programmatic logic and atomic transactions. but i see the point anyway.

as i cannot find the error message you refer to in the mysql manual, try checking for an error code betwen 1215 and 1217 (foreign key constraints).

$errorCode = mysql_errorno();
if ($errorCode <= 1215 && $errorCode >= 1217){
 echo "some message about constraints";
}

 

[HughbertD]

When I try mysql_errorno() I get call to undefined function.

Is there a built in function to get the errorno?

 

[HughbertD]

Ah its mysql_errno() however, I don't think the error falls within 1215-1217.

 

[jpadie]

then find out what the error number is and capture that. as i said, i could not find anything in the mysql manual (for 5.0) that corresponded to the error message you reported.

 

[HughbertD]

Sorry, I already did this, after I stopped being lazy.

Thanks for the help!

(It was 1451)