PHP MySQL error handling

Question

Simple question (I hope).

At the moment I am using the following code:

mysql_query($sql) or header("Location: /error");

To prevent the rest of the script running I need to add exit; or die(). Is there any way to do that using the inline approach as above or do I need to use:

$result = mysql_query($sql);
if (!result) {
    header("Location: /error");
    exit();
}

Thanks

score 11 · Accepted Answer · answered Nov 08 '10 at 16:07

11

How about:

function customDie($location) {
    header('Location: ' . $location);
    exit();
}


mysql_query($sql) or customDie("/error");

answered Nov 08 '10 at 16:07

Fosco

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score 6 · Answer 2 · edited Feb 24 '12 at 12:45

If you insist on doing things this way it is better to make a custom query method which handles all this. Something like

function custom_mysql_query($query) {
  $doDebug=true; // Set to true when developing and false when you are deploying for real.

  $result=mysql_query($query);
  if(!$result) {
    if($doDebug) {
       // We are debugging so show some nice error output
       echo "Query failed\n<br><b>$query</b>\n";
       echo mysql_error(); // (Is that not the name)
     }
     else {
      // Might want an error message to the user here.
     }
     exit();
  }
}

Then just call custom_mysql_query instead of mysql_query then you will always die if a query fails and if $debug is true, you will also get the query which failed and the database error.

But really: You should NEVER use mysql_query or functions which call it(Such as the one I just wrote). It is far too unsafe to ever be used. (Far too difficult to avoid sql injections)

Use the pdo classes instead of the mysql_ methods(Google it, there are many tutorials and explanations online).

score 1 · Answer 3 · answered Nov 08 '10 at 16:08

You could check if there was a MySQL error. If you need to do the check later do something like:

$result = mysql_query($sql);
$error = mysql_error() != '' ? true : false;

/* fancy code */

if($error)
{
     header(location: url);
     exit;
}

Edit: I misread your question and now see that you want to kill it if there's an error so you could just do:

if(mysql_error() != '')
{
     header();
     exit;
}

score 0 · Answer 4 · answered Nov 08 '10 at 16:10

$db = mysql_connect(//database info);

$result = mysql_query(//query);
if (mysql_error($db) != '')
{
  header("Location: /error");
  exit();
}

If there isn't an error after the query completes, the code continues. Otherwise, the user is redirected and the code stops executing.

PHP MySQL error handling

4 Answers4

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