How can i get exception from mysql in php?

Elaborating on yasaluyari's answer I would stick with something like this:

We can just modify our mysql_query as follows:

function mysql_catchquery($query,$emsg='Error submitting the query'){
    if ($result=mysql_query($query)) return $result;
    else throw new Exception($emsg);
}

Now we can simply use it like this, some good example:

try {
    mysql_catchquery('CREATE TEMPORARY TABLE a (ID int(6))');
    mysql_catchquery('insert into a values(666),(418),(93)');
    mysql_catchquery('insert into b(ID, name) select a.ID, c.name from a join c on a.ID=c.ID');
    $result=mysql_catchquery('select * from d where ID=7777777');
    while ($tmp=mysql_fetch_assoc($result)) { ... }
} catch (Exception $e) {
    echo $e->getMessage();
}

Note how beautiful it is. Whenever any of the qq fails we gtfo with our errors. And you can also note that we don't need now to store the state of the writing queries into a $result variable for verification, because our function now handles it by itself. And the same way it handles the selects, it just assigns the result to a variable as does the normal function, yet handles the errors within itself.

Also note, we don't need to show the actual errors since they bear huge security risk, especially so with this outdated extension. That is why our default will be just fine most of the time. Yet, if we do want to notify the user for some particular query error, we can always pass the second parameter to display our custom error message.

(PHP 4, PHP 5)

mysql_errorReturns the text of the error message from previous MySQL operation

Description

mysql_error(resource $link_identifier = NULL): string

Parameters

link_identifier

The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() had been called with no arguments. If no connection is found or established, an E_WARNING level error is generated.

Return Values

Returns the error text from the last MySQL function, or '' (empty string) if no error occurred.

Examples

Example #1 mysql_error() example

$link mysql_connect("localhost""mysql_user""mysql_password");mysql_select_db("nonexistentdb"$link);
echo 
mysql_errno($link) . ": " mysql_error($link). "\n";mysql_select_db("kossu"$link);
mysql_query("SELECT * FROM nonexistenttable"$link);
echo 
mysql_errno($link) . ": " mysql_error($link) . "\n";
?>

The above example will output something similar to:

1049: Unknown database 'nonexistentdb'
1146: Table 'kossu.nonexistenttable' doesn't exist

See Also

  • mysql_errno() - Returns the numerical value of the error message from previous MySQL operation
  • » MySQL error codes

aleczapka _at) gmx dot net

18 years ago

If you want to display errors like "Access denied...", when mysql_error() returns "" and mysql_errno() returns 0, use  $php_errormsg. This Warning will be stored there.  You need to have track_errors set to true in your php.ini.

Note. There is a bug in either documentation about error_reporting() or in mysql_error() function cause manual for mysql_error(), says:  "Errors coming back from the MySQL database backend no longer issue warnings." Which is not true.

Florian Sidler

12 years ago

Be aware that if you are using multiple MySQL connections you MUST support the link identifier to the mysql_error() function. Otherwise your error message will be blank.

Just spent a good 30 minutes trying to figure out why i didn't see my SQL errors.

Pendragon Castle

13 years ago

Using a manipulation of josh ><>'s function, I created the following. It's purpose is to use the DB to store errors. It handles both original query, as well as the error log. Included Larry Ullman's escape_data() as well since I use it in q().

function escape_data($data){
global
$dbc;
if(
ini_get('magic_quotes_gpc')){
 
$data=stripslashes($data);
}
return
mysql_real_escape_string(trim($data),$dbc);
}

function

q($page,$query){
// $page
$result = mysql_query($query);
if (
mysql_errno()) {
 
$error = "MySQL error ".mysql_errno().": ".mysql_error()."\n
When executing:
\n
$query\n
"
;
 
$log = mysql_query("INSERT INTO db_errors (error_page,error_text) VALUES ('$page','".escape_data($error)."')");
}
}
// Run the query using q()
$query = "INSERT INTO names (first, last) VALUES ('myfirst', 'mylast'");
$result = q("Sample Page Title",$query);
?>

Anonymous

17 years ago

My suggested implementation of mysql_error():

$result = mysql_query($query) or die("A fatal MySQL error occured.\n
Query: " . $query . "
\nError: (" . mysql_errno() . ") " . mysql_error());

This will print out something like...

A fatal MySQL error occured.
Query: SELECT * FROM table
Error: (err_no) Bla bla bla, you did everything wrong

It's very useful to see your query in order to detect problems with syntax. Most often, the output message from MySQL doesn't let you see enough of the query in the error message to let you see where your query went bad- it a missing quote, comma, or ( or ) could have occured well before the error was detected. I do -not- recomend using this procedure, however, for queries which execute on your site that are not user-specific as it has the potential to leak sensative data. Recomended use is just for debugging/building a script, and for general user-specific queries which would at the worst, leak the users own information to themself.

Good luck,

-Scott

olaf at amen-online dot de

18 years ago

When dealing with user input, make sure that you use
echo htmlspecialchars (mysql_error ());
?>
instead of
echo mysql_error ();
?>

Otherwise it might be possible to crack into your system by submitting data that causes the SQL query to fail and that also contains javascript commands.

Would it make sense to change the examples in the documentation for mysql_query () and for mysql_error () accordingly?

l dot poot at twing dot nl

16 years ago

When creating large applications it's quite handy to create a custom function for handling queries. Just include this function in every script. And use db_query(in this example) instead of mysql_query.

This example prompts an error in debugmode (variable $b_debugmode ). An e-mail with the error will be sent to the site operator otherwise.

The script writes a log file in directory ( in this case /log ) as well.

The system is vulnerable when database/query information is prompted to visitors. So be sure to hide this information for visitors anytime.

Regars,

Lennart Poot
http://www.twing.nl

$b_debugmode = 1; // 0 || 1$system_operator_mail = '';
$system_from_mail = '';

function

db_query( $query ){
  global
$b_debugmode;// Perform Query
 
$result = mysql_query($query);// Check result
  // This shows the actual query sent to MySQL, and the error. Useful for debugging.
 
if (!$result) {
    if(
$b_debugmode){
     
$message  = 'Invalid query:
'
. mysql_error() . '

'
;
     
$message .= 'Whole query:
'
. $query . '

'
;
      die(
$message);
    }
raise_error('db_query_error: ' . $message);
  }
  return
$result;
}

  function

raise_error( $message ){
    global
$system_operator_mail, $system_from_mail;$serror=
   
"Env:       " . $_SERVER['SERVER_NAME'] . "\r\n" .
   
"timestamp: " . Date('m/d/Y H:i:s') . "\r\n" .
   
"script:    " . $_SERVER['PHP_SELF'] . "\r\n" .
   
"error:     " . $message ."\r\n\r\n";// open a log file and write error
   
$fhandle = fopen( '/logs/errors'.date('Ymd').'.txt', 'a' );
    if(
$fhandle){
     
fwrite( $fhandle, $serror );
     
fclose(( $fhandle ));
     }
// e-mail error to system operator
   
if(!$b_debugmode)
     
mail($system_operator_mail, 'error: '.$message, $serror, 'From: ' . $system_from_mail );
  }
?>

Gianluigi_Zanettini-MegaLab.it

15 years ago

"Errors coming back from the MySQL database backend no longer issue warnings." Please note, you have an error/bug here. In fact, MySQL 5.1 with PHP 5.2:

Warning: mysql_connect() [function.mysql-connect]: Unknown MySQL server host 'locallllllhost' (11001)

That's a warning, which is not trapped by mysql_error()!

Anonymous

21 years ago

some error can't handle. Example:

ERROR 1044: Access denied for user: '' to database 'itcom'

This error ocurrs when a intent of a sql insert of no authorized user. The results: mysql_errno = 0 and the mysql_error = "" .

scott at rocketpack dot net

19 years ago

My suggested implementation of mysql_error():

$result = mysql_query($query) or die("A fatal MySQL error occured.\n
Query: " . $query . "
\nError: (" . mysql_errno() . ") " . mysql_error());

This will print out something like...

A fatal MySQL error occured.
Query: SELECT * FROM table
Error: (err_no) Bla bla bla, you did everything wrong

It's very useful to see your query in order to detect problems with syntax. Most often, the output message from MySQL doesn't let you see enough of the query in the error message to let you see where your query went bad- it a missing quote, comma, or ( or ) could have occured well before the error was detected. I do -not- recomend using this procedure, however, for queries which execute on your site that are not user-specific as it has the potential to leak sensative data. Recomended use is just for debugging/building a script, and for general user-specific queries which would at the worst, leak the users own information to themself.

Good luck,

-Scott

josh ><>

18 years ago

Oops, the code in my previous post only works for queries that don't return data (INSERT, UPDATE, DELETE, etc.), this updated function should work for all types of queries (using $result = myquery($query);):

    function myquery ($query) {
        $result = mysql_query($query);
        if (mysql_errno())
            echo "MySQL error ".mysql_errno().": ".mysql_error()."\n
When executing:
\n$query\n
";
        return $result;
    }

phpnet at robzazueta dot com

15 years ago

This is a big one - As of MySQL 4.1 and above, apparently, the way passwords are hashed has changed. PHP 4.x is not compatible with this change, though PHP 5.0 is. I'm still using the 4.x series for various compatibility reasons, so when I set up MySQL 5.0.x on IIS 6.0 running PHP 4.4.4 I was surpised to get this error from mysql_error():

MYSQL: Client does not support authentication protocol requested by server; consider upgrading MySQL client

According to the MySQL site (http://dev.mysql.com/doc/refman/5.0/en/old-client.html) the best fix for this is to use the OLD_PASSWORD() function for your mysql DB user. You can reset it by issuing to MySQL:

Set PASSWORD for 'user'@'host' = OLD_PASSWORD('password');

This saved my hide.

Gianluigi_Zanettini-MegaLab.it

15 years ago

A friend of mine proposed a great solution.

$old_track = ini_set('track_errors', '1');

.....

        if (

$this->db_handle!=FALSE && $db_selection_status!=FALSE)
            {
           
$this->connected=1;
           
ini_set('track_errors', $old_track);
            }
        else
            {
           
$this->connected=-1;
           
$mysql_warning=$php_errormsg;
           
ini_set('track_errors', $old_track);
            throw new
mysql_cns_exception(1, $mysql_warning . " " . mysql_error());
            }
?>

Gerrit

8 years ago

The following code returns two times the same error, even though I would have expected only one:

   $ conn = mysql_connect ('localhost', 'root', '');
   $ conn2 = mysql_connect ('localhost', 'root', '');

     mysql_select_db ('db1', $ conn);
   mysql_select_db ('db2', $ conn2);

     $ result = mysql_query ("select 1 from dual", $ conn);
   $ result2 = mysql_query ("select 1 from luad", $ conn2);

     echo mysql_error ($ conn) "


".
   echo mysql_error ($ conn2) "
".

The reason for this is that mysql_connect not working as expected a further connection returns. Since the parameters are equal, a further reference to the previous link is returned. So also changes the second mysql_select_db the selected DB of $conn to 'db2'.

If you change the connection parameters of the second connection to 127.0.0.1, a new connection is returned. In addition to the parameters new_link the mysql_connect() function to be forced.

How can I get MySQL error code in PHP?

Description ¶ Instead, use mysql_error() to retrieve the error text. Note that this function only returns the error text from the most recently executed MySQL function (not including mysql_error() and mysql_errno()), so if you want to use it, make sure you check the value before calling another MySQL function.

How can I catch exception in PHP?

Because exceptions are objects, they all extend a built-in Exception class (see Throwing Exceptions in PHP), which means that catching every PHP exception thrown is as simple as type-hinting the global exception object, which is indicated by adding a backslash in front: try { // ... } catch ( \Exception $e ) { // ... }

How do I find MySQL errors?

You can also examine the errmsg. h file in the include directory of a MySQL source distribution. The built-in variable $mysql_errno contains the numeric error returned by the most recent SQL statement sent to the server, or 0 if the statement executed successfully.

How does PHP handle SQL errors?

You can use: if (mysqli_error($conn)) { $error = 'Oops something went wrong!'; } echo $error; The $conn stands for the database connection through which the query was carried out.