mysql_error

(PHP 4, PHP 5)

mysql_error返回上一个 MySQL 操作中的错误信息的文本

警告

本扩展自 PHP 5.5.0 起已废弃,并在自 PHP 7.0.0 开始被移除。应使用 MySQLiPDO_MySQL 扩展来替换之。参见 MySQL:选择 API 指南来获取更多信息。用以替代本函数的有:

说明

mysql_error(resource $link_identifier = NULL): string

返回上一个 MySQL 函数的错误文本。 从 MySQL 数据库后端来的错误不再发出警告。要用 mysql_error() 来检索错误文本。注意本函数仅返回最近执行的 MySQL 函数(不包括 mysql_error()mysql_errno())的错误文本,因此如果要使用此函数,确保在调用另一个 MySQL 函数之前检查它的值。

参数

link_identifier

MySQL 连接。如不指定连接标识,则使用由 mysql_connect() 最近打开的连接。如果没有找到该连接,会尝试不带参数调用 mysql_connect() 来创建。如没有找到连接或无法建立连接,则会生成 E_WARNING 级别的错误。

返回值

返回上一个 MySQL 函数的错误文本,如果没有出错则返回 ''(空字符串)。

示例

示例 #1 mysql_error() 示例

<?php
$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";
?>

以上示例的输出类似于:

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

参见

添加备注

用户贡献的备注 13 notes

up
9
aleczapka _at) gmx dot net
20 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.
up
4
l dot poot at twing dot nl
18 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

<?php
$b_debugmode
= 1; // 0 || 1

$system_operator_mail = 'developer@company.com';
$system_from_mail = 'info@mywebsite.com';

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 = '<b>Invalid query:</b><br>' . mysql_error() . '<br><br>';
$message .= '<b>Whole query:</b><br>' . $query . '<br><br>';
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 );
}

?>
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2
Florian Sidler
14 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.
up
1
Pendragon Castle
15 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().

<?php
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()) {
$error = "MySQL error ".mysql_errno().": ".mysql_error()."\n<br>When executing:<br>\n$query\n<br>";
$log = mysql_query("INSERT INTO db_errors (error_page,error_text) VALUES ('$page','".escape_data($error)."')");
}
}

// Run the query using q()
$query = "INSERT INTO names (first, last) VALUES ('myfirst', 'mylast'");
$result = q("Sample Page Title",$query);
?>
up
-2
olaf at amen-online dot de
20 years ago
When dealing with user input, make sure that you use
<?php
echo htmlspecialchars (mysql_error ());
?>
instead of
<?php
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?
up
-2
Anonymous
23 years ago
some error can't handle. Example:

ERROR 1044: Access denied for user: 'ituser@mail.ramon.intranet' 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 = "" .
up
-3
Anonymous
19 years ago
My suggested implementation of mysql_error():

$result = mysql_query($query) or die("<b>A fatal MySQL error occured</b>.\n<br />Query: " . $query . "<br />\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
up
-3
josh ><>
21 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<br>When executing:<br>\n$query\n<br>";
return $result;
}
up
-4
scott at rocketpack dot net
21 years ago
My suggested implementation of mysql_error():

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

This will print out something like...

<b>A fatal MySQL error occured</b>.
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
up
-4
Gianluigi_Zanettini-MegaLab.it
17 years ago
A friend of mine proposed a great solution.

<?php
$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());
}
?>
up
-5
Gianluigi_Zanettini-MegaLab.it
17 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()!
up
-5
phpnet at robzazueta dot com
17 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.
up
-5
miko_il AT yahoo DOT com
20 years ago
Following are error codes that may appear when you call MySQL from any host language:

http://www.mysql.com/doc/en/Error-returns.html
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