(PHP 4, PHP 5)
mysql_error — Возвращает текст ошибки последней операции с MySQL
Описание
mysql_error(resource $link_identifier
= NULL): string
Список параметров
-
link_identifier
-
Соединение MySQL. Если идентификатор соединения не был указан,
используется последнее соединение, открытое mysql_connect(). Если такое соединение не было найдено,
функция попытается создать таковое, как если бы mysql_connect() была вызвана без параметров.
Если соединение не было найдено и не смогло быть создано, генерируется ошибка уровняE_WARNING
.
Возвращаемые значения
Возвращает текст ошибки выполнения последней функции MySQL,
или ''
(пустую строку), если операция
выполнена успешно.
Примеры
Пример #1 Пример использования mysql_error()
<?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";
?>
Результатом выполнения данного примера
будет что-то подобное:
1049: Unknown database 'nonexistentdb' 1146: Table 'kossu.nonexistenttable' doesn't exist
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 $php_errormsg. This Warning will be stored there. You need to have track_errors set to true in your php.ini.
Note. There is a bug in either documentation about error_reporting() or in mysql_error() function cause manual for mysql_error(), says: "Errors coming back from the MySQL database backend no longer issue warnings." Which is not true.
Pendragon Castle ¶
14 years ago
Using a manipulation of josh ><>'s function, I created the following. It's purpose is to use the DB to store errors. It handles both original query, as well as the error log. Included Larry Ullman's escape_data() as well since I use it in q().
<?php
function escape_data($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()) {
$error = "MySQL error ".mysql_errno().": ".mysql_error()."n<br>When executing:<br>n$queryn<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);
?>
Florian Sidler ¶
13 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.
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
<?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'] . "rn" .
"timestamp: " . Date('m/d/Y H:i:s') . "rn" .
"script: " . $_SERVER['PHP_SELF'] . "rn" .
"error: " . $message ."rnrn";// 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 );
}?>
Anonymous ¶
22 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 = "" .
Anonymous ¶
18 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
olaf at amen-online dot de ¶
19 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?
josh ><> ¶
19 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$queryn<br>";
return $result;
}
Gianluigi_Zanettini-MegaLab.it ¶
16 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());
}
?>
scott at rocketpack dot net ¶
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...
<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
Gianluigi_Zanettini-MegaLab.it ¶
16 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()!
phpnet at robzazueta dot com ¶
16 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.
miko_il AT yahoo DOT com ¶
19 years ago
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) "<hr>".
echo mysql_error ($ conn2) "<hr>".
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 $conn to 'db2'.
If you change the connection parameters of the second connection to 127.0.0.1, a new connection is returned. In addition to the parameters new_link the mysql_connect() function to be forced.
За последние 24 часа нас посетили 12316 программистов и 1161 робот. Сейчас ищут 747 программистов …
mysqli::$error
mysqli_error
(PHP 5, PHP 7)
mysqli::$error — mysqli_error — Возвращает строку с описанием последней ошибки
Описание
Объектно-ориентированный стиль
Процедурный стиль
string mysqli_error
( mysqli $link
)
Возвращаемые значения
Строка с описанием ошибки. Пустая строка, если ошибки нет.
Примеры
Пример #1 Пример с $mysqli->error
Объектно-ориентированный стиль
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");/* check connection */
if ($mysqli->connect_errno) {
printf("Connect failed: %sn", $mysqli->connect_error);
exit();
}
if (!
$mysqli->query("SET a=1")) {
printf("Errormessage: %sn", $mysqli->error);
}/* close connection */
$mysqli->close();
?>
Процедурный стиль
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %sn", mysqli_connect_error());
exit();
}
if (!
mysqli_query($link, "SET a=1")) {
printf("Errormessage: %sn", mysqli_error($link));
}/* close connection */
mysqli_close($link);
?>
Результат выполнения данных примеров:
Errormessage: Unknown system variable 'a'
Смотрите также
- mysqli_connect_errno() — Возвращает код ошибки последней попытки соединения
- mysqli_connect_error() — Возвращает описание последней ошибки подключения
- mysqli_errno() — Возвращает код ошибки последнего вызова функции
- mysqli_sqlstate() — Возвращает код состояния SQLSTATE последней MySQL операции
Вернуться к: mysqli
Really, it drive me crazy when I can’t detect what error that happens. I can’t handle it.
I managed to make a connection to MySQL, and check it out with:
$connection = mysqli_connect(HOST, USER, PASS, DB) or die('Could not connect!');
if($connection){
echo 'It's connected!';
}
Yeah, that say connected. Then, when I try a query, it fails without error reporting. I’ve tried do this to check if it fails:
$query = "SELECT $field FROM users WHERE id = ".$_SESSION['user_id'];
$result = mysqli_query($dbc, $query);
if($result){
echo 'Query OK';
}else{
echo 'Query failed';
}
The browser said: Query failed. So, there’s an error in my query. Then I echoed the query out with this:
echo $query;
// Printed in the browser: SELECT firstname FROM users WHERE id = 1
Copy that value and use it in phpMyAdmin. It works. So, i guess an error occured in mysqli_query
function. But i can’t get the error message and so i don’t know what’s going on. I’ve tried this:
$result = mysqli_query($dbc, $query) or die(mysqli_error($dbc));
and this:
if(!$result){
echo mysqli_error($dbc);
}
Nothing happens. The browser just blank. Then, I tried to change this:
$result = mysqli_query($dbc, $query);
to this:
$result = mysqli_query($query);
Still nothing happens. What’s going on? How can I know what error occured?
I run the server in Debian with phpinfo()
: PHP Version 5.4.36-0+deb7u3
PHP | mysqli_error() Function
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The mysqli_error() function is used to return the error in the most recent MySQL function call that failed. If there are multiple MySQL function calls, the error in the last statement is the one that is pointed out by the function.
Syntax:
mysqli_error("database_name")
Parameters: This function accepts single parameter as mentioned above and described below:
- database_name: It is the database on which operations are being performed. It is a mandatory parameter.
Program 1:
<?php
$conn
= mysqli_connect(
"localhost"
,
"root"
,
""
,
"Persons"
);
if
(mysqli_connect_errno()) {
echo
"Database connection failed."
;
}
if
(!mysqli_query(
$link
,
"SET Age=1"
)) {
printf(
"Error message: %sn"
, mysqli_error(
$conn
));
}
mysqli_close(
$conn
);
?>
Suppose the operation is being carried out on the table given below:
The output will be:
Error message: Unknown system variable 'Age'
Program 2:
<?php
$conn
= mysqli_connect(
"localhost"
,
"root"
,
""
,
"Persons"
);
if
(mysqli_connect_errno()) {
echo
"Database connection failed."
;
}
if
(!mysqli_query(
$link
,
"SET Firstname='Arkadyuti'"
)) {
printf(
"Error message: %sn"
, mysqli_error());
}
mysqli_close(
$conn
);
?>
Output:
Error message: mysqli_error() expects exactly 1 parameter, 0 given
This example also demonstrates that mysqli_error() needs a database as a parameter.
Last Updated :
23 Apr, 2020
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- PHP
MySQLi
Error Functions - Conclusion
MySQLi
is a PHP function used to access the MySQL database server. You can use this extension if you have MySQL version 4.1.13 or above.
There are various MySQLi
functions that you can use to perform different functions in PHP. In this article, we will learn MySQLi
error functions.
We will also see how and where to use code examples and observe the outputs. For this tutorial, we will use MySQL version 8.0.27 and PHP version 7.4.1.
PHP MySQLi
Error Functions
In this tutorial, we will learn about the following PHP MySQLi
error functions:
mysqli_error()
mysqli_errno()
mysqli_error_list()
mysqli_connect_error()
mysqli_connect_errno()
All these functions can be used in object-oriented style and procedural style. Let’s understand both syntax using the mysqli_error()
function.
Syntax of mysqli_error()
Function in Object Oriented Style
Syntax of mysqli_error()
Function in Procedural Style
string mysqli_error ( mysqli $link )
mysqli_error()
Function in MySQL
This function is used to output the last error description for the most recent function call (if there is any). It is used when you want to know whether the SQL
query has an error or not.
mysqli_error()
returns the error description and empty string if there is no error. See the following example.
Example Code Using Procedural Style:
<?php
$host = "localhost";
$username = "root";
$password = "";
$database = "person";
$connection = mysqli_connect($host, $username, $password, $database)
or die("Connection Failed");
$sql = "SELECT * FROM teacher";
$result = mysqli_query($connection, $sql);
$error_message = mysqli_error($connection);
if($error_message == ""){
echo "No error related to SQL query.";
}else{
echo "Query Failed: ".$error_message;
}
mysqli_close($connection);
?>
The code given above tries to make the connection using $host
, $username
, $password
, $database
variables and save this connection into the $connection
variable.
mysqli_error()
function will take this connection variable $connection
as a parameter and check if there is any error caused by the recent MySQLi
function call which is mysqli_query($connection, $sql)
here.
Output:
Now, change the table name in the SQL
query from teacher
to person
and observe the output given below.
Output:
We, as a developer, can easily understand that there is no person
table in the person
database (this is what it means in the above error).
Keep the table name changed and replace the line $error_message = mysqli_error($connection);
with $error_message = $connection->error;
to practice and understand the object oriented style using MySQLi
error function.
mysqli_errno()
Function in MySQL
mysqli_errno()
works the same as mysqli_error()
does, but it will return the error code instead of the error description.
Write the following code to practice and understand. You may have noticed that we use a procedural style to practice this function.
<?php
$host = "localhost";
$username = "root";
$password = "";
$database = "person";
$connection = mysqli_connect($host, $username, $password, $database)
or die("Connection Failed");
$sql = "SELECT * FROM person";
$result = mysqli_query($connection, $sql);
$error_message = mysqli_errno($connection);
if($error_message == ""){
echo "No error related to SQL query.";
}else{
echo "Query Failed: ".$error_message;
}
mysqli_close($connection);
?>
The code given above will show the following output where you will see a number as an error code.
Output:
The question is, why do we use this function to show the numbers only? Because if you want to print a user-friendly error message (custom message), you can use this error code in if-else
statements.
See the following code and its output below.
<?php
$host = "localhost";
$username = "root";
$password = "";
$database = "person";
$connection = mysqli_connect($host, $username, $password, $database)
or die("Connection Failed");
$sql = "SELECT * FROM person";
$result = mysqli_query($connection, $sql);
$error_message = mysqli_errno($connection);
if($error_message == 1146){
echo "You are trying to read the data from a table which doesn't exist in your database "."'".$database."'";
}
mysqli_close($connection);
?>
Output:
mysqli_error_list()
Function in MySQL
This function is very useful for knowing the error code, SQL state, and error description because this function returns an array containing all the necessary information.
Example Code:
<?php
$host = "localhost";
$username = "root";
$password = "";
$database = "person";
$connection = mysqli_connect($host, $username, $password, $database)
or die("Connection Failed");
$sql = "SELECT * FROM person";
$result = mysqli_query($connection, $sql);
print_r(mysqli_error_list($connection));
mysqli_close($connection);
?>
Output:
mysqli_connect_error()
Function in MySQL
mysqli_connect_error()
returns the error description from the last connection if there is any. Although, the die()
function also tell about the unsuccessful connection but mysqli_connect_error()
returns the error that we can understand easily.
Write the following code first, see its output, and then we’ll compare it with the output produced by mysqli_connect_error()
.
<?php
$host = "localhost";
$username = "root";
$password = "";
$database = "person";
$connection = mysqli_connect($host, $username, $password, $database)
or die("Connection Failed");
$sql = "SELECT * FROM person";
$result = mysqli_query($connection, $sql);
$error_message = mysqli_error($connection);
if($error_message != ""){
echo "Query Failed: ".$error_message;
}
mysqli_close($connection);
?>
Output:
See the output given above; you can see that the error we can understand is somewhere in the middle.
Imagine, if you have 2 or 3 errors, it would not be easy to find out. Now, use the mysqli_connect_error()
and see the difference using the following code and output.
<?php
$host = "localhost";
$username = "newroot";
$password = "";
$database = "person";
$connection = mysqli_connect($host, $username, $password, $database)
or die("Connection Failed: ".mysqli_connect_error());
$sql = "SELECT * FROM teacher";
$result = mysqli_query($connection, $sql);
$error_message = mysqli_error($connection);
if($error_message != ""){
echo "SQL Query Failed: ".$error_message;
}
mysqli_close($connection);
?>
Output:
The above output clearly says that there is no user named newroot
, which does not allow you to access the database.
mysqli_connect_errno()
Function in MySQL
This function behaves like mysqli_connect_error()
but displays the error code rather than the error message. We can use this error code to write custom error messages.
Example Code:
<?php
$host = "localhost";
$username = "newroot";
$password = "";
$database = "person";
$connection = mysqli_connect($host, $username, $password, $database)
or die("Connection Failed: ".mysqli_connect_errno());
$sql = "SELECT * FROM teacher";
$result = mysqli_query($connection, $sql);
$error_message = mysqli_error($connection);
if($error_message != ""){
echo "SQL Query Failed: ".$error_message;
}
mysqli_close($connection);
?>
Output:
Conclusion
Considering all the discussion and examples, we have concluded two main categories. The first category shows the errors about SQL queries and the other about database connections.
Depending on the project needs, we can print the error message or the error code in each category.