Mysqli last error

mysqli::$error — Возвращает строку с описанием последней ошибки

mysqli_error

mysqli::$error — mysqli_error — Возвращает строку с описанием последней ошибки

Описание

Возвращает сообщение об ошибке последнего вызова функции MySQLi, который может успешно выполниться или провалиться.

Список параметров

Только для процедурного стиля: Идентификатор соединения, полученный с помощью mysqli_connect() или mysqli_init()

Возвращаемые значения

Строка с описанием ошибки. Пустая строка, если ошибки нет.

Примеры

Пример #1 Пример с $mysqli->error

= 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 ();
?>

= 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:

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

Источник

How to report errors in mysqli

Add the following line before mysqli_connect() (or new mysqli() ):

Introduction

Reporting errors is the most essential thing in programming. A programmer is effectively deaf-blind if they cannot see errors occurred during the script execution. So it is very important to configure error reporting for your code properly, including database interactions.

By default, when you are running mysqli_query() or — preferably — prepare()/bind()/execute() , mysqli will just silently return false if a query fails, telling you nothing of the reason.

You’ll notice the error only when the following command, when trying to use the query result, will raise an error, such as

Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given.

Unfortunately, this error message tells you nothing of the actual problem. It just bluntly says that your query failed, and nothing else.

It happens because by default mysqli is configured to remain silent if a query returned an error. So you can tell that’s an extremely inconvenient behavior.

Luckily, mysqli can be configured to throw a PHP exception in case of a mysql error. It means that a PHP error will be thrown automatically every time a query returns an error, without any effort on your part!

Let’s see a small demonstration:

And run your script again. Whoa! An error appears in a puff of smoke, explaining what was the problem:

As you can see, this is quite a detailed information, including the erroneous part of the query, and even a stack trace that helps you to find a particular function that called the erroneous query.

So again: just make sure that you always have this magic line before mysqli_connect() in all your scripts:

What to do with the error message you get?

It should be a knee-jerk reflex to copy and paste the error message in Google search. It will lead you to several Stack Overflow questions related to this particular problem with many answers with solutions.

However, there is another possibility. You can try to actually read the error message you get. Usually, the error message explains it pretty straightforward, what is the error. However, some errors could be cryptic. You have to understand some considerations used in Mysql error messages:

• in case of a syntax error, the cited query part begins right after the error.
• it means that, therefore, if the error is at the very end of the query, the cited query part would be an empty string. Most likely it happens when you add a variable directly to the query and this variable happen to be empty (yet another reason to use prepared statements as they will make such errors just impossible to appear.

Related articles:

Got a question?

I am the only person to hold a gold badge in , and on Stack Overflow and I am eager to show the right way for PHP developers.

Besides, your questions let me make my articles even better, so you are more than welcome to ask any question you have.

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bind_param() seems not to throw an exception, only errors. what do you advice us to do in this case?

Reply:

That’s an interesting question. The simplest solution would be to upgrade the PHP version. Starting from 8.0 bind_param is throwing exceptions all right.

For the older versions, it depends on what you need the exception for. Normally, there should be no difference: a Warning as in error all the same, it will be reported and the next call to execute will halt the code execution.

But if you really need and exception, you can add a simple error handler to your code that would convert all errors to excepions, like

Hope some of these suggestions will help. If not, then please let me know.

a bit misleading if all you have to do is call mysqli_error() and mysqli_errno() no need to reconfigure anything.

Reply:

There are two problems with this mindset.

First, the logic is somewhat inverted here: as long as you have to run only one SQL query, there is not much difference. But even with a dozen, not to mention hundreds of SQL queries, this «call mysqli_error() and mysqli_errno()» after every query becomes «a bit misleading». Now compare it with just «reconfiguring» a single line of code.

Second, the question is, what you’re going to do with all these mysqli_error() and mysqli_errno() calls. Are you sure you are going to use them properly? And what if some day you will decide to change that behavior? For example, now you want to die() with the error message but eventually you will learn that it’s just gross and it needs to be changed. So, which approach will make it simpler: when you have just a single place where error reporting is configured, or when you have dozens to hundreds places where you need to rewrite the code?

Источник

mysqli::$error

(PHP 5, PHP 7, PHP

mysqli::$error — mysqli_error — Returns a string description of the last error

Description

Returns the last error message for the most recent MySQLi function call that can succeed or fail.

Parameters

Procedural style only: A mysqli object returned by mysqli_connect() or mysqli_init()

Return Values

A string that describes the error. An empty string if no error occurred.

Examples

Example #1 $mysqli->error example

= 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 ( «Error message: %sn» , $mysqli -> error );
>

/* close connection */
$mysqli -> close ();
?>

= 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 ( «Error message: %sn» , mysqli_error ( $link ));
>

/* close connection */
mysqli_close ( $link );
?>

The above examples will output:

See Also

• mysqli_connect_errno() — Returns the error code from last connect call
• mysqli_connect_error() — Returns a description of the last connection error
• mysqli_errno() — Returns the error code for the most recent function call
• mysqli_sqlstate() — Returns the SQLSTATE error from previous MySQL operation

User Contributed Notes 7 notes

The mysqli_sql_exception class is not available to PHP 5.05

I used this code to catch errors
= «SELECT XXname FROM customer_table » ;
$res = $mysqli -> query ( $query );

if (! $res ) <
printf ( «Errormessage: %sn» , $mysqli -> error );
>

?>
The problem with this is that valid values for $res are: a mysqli_result object , true or false
This doesn’t tell us that there has been an error with the sql used.
If you pass an update statement, false is a valid result if the update fails.

So, a better way is:
= «SELECT XXname FROM customer_table » ;
$res = $mysqli -> query ( $query );

if (! $mysqli -> error ) <
printf ( «Errormessage: %sn» , $mysqli -> error );
>

?>

This would output something like:
Unexpected PHP error [mysqli::query() [function.query]: (42S22/1054): Unknown column ‘XXname’ in ‘field list’] severity [E_WARNING] in [G:database.php] line [249]

Very frustrating as I wanted to also catch the sql error and print out the stack trace.

A better way is:

( MYSQLI_REPORT_OFF ); //Turn off irritating default messages

$mysqli = new mysqli ( «localhost» , «my_user» , «my_password» , «world» );

$query = «SELECT XXname FROM customer_table » ;
$res = $mysqli -> query ( $query );

if ( $mysqli -> error ) <
try <
throw new Exception ( «MySQL error $mysqli -> error
Query:
$query » , $msqli -> errno );
> catch( Exception $e ) <
echo «Error No: » . $e -> getCode (). » — » . $e -> getMessage () . «
» ;
echo nl2br ( $e -> getTraceAsString ());
>
>

//Do stuff with the result
?>
Prints out something like:
Error No: 1054
Unknown column ‘XXname’ in ‘field list’
Query:
SELECT XXname FROM customer_table

#0 G:\database.php(251): database->dbError(‘Unknown column . ‘, 1054, ‘getQuery()’, ‘SELECT XXname F. ‘)
#1 G:dataWorkSites1framework5testsdbtest.php(29): database->getString(‘SELECT XXname F. ‘)
#2 c:PHPincludessimpletestrunner.php(58): testOfDB->testGetVal()
#3 c:PHPincludessimpletestrunner.php(96): SimpleInvoker->invoke(‘testGetVal’)
#4 c:PHPincludessimpletestrunner.php(125): SimpleInvokerDecorator->invoke(‘testGetVal’)
#5 c:PHPincludessimpletestrunner.php(183): SimpleErrorTrappingInvoker->invoke(‘testGetVal’)
#6 c:PHPincludessimpletestsimple_test.php(90): SimpleRunner->run()
#7 c:PHPincludessimpletestsimple_test.php(498): SimpleTestCase->run(Object(HtmlReporter))
#8 c:PHPincludessimpletestsimple_test.php(500): GroupTest->run(Object(HtmlReporter))
#9 G:all_tests.php(16): GroupTest->run(Object(HtmlReporter))

This will actually print out the error, a stack trace and the offending sql statement. Much more helpful when the sql statement is generated somewhere else in the code.

The decription «mysqli_error — Returns a string description of the LAST error» is not exactly that what you get from mysqli_error. You get the error description from the last mysqli-function, not from the last mysql-error.

If you have the following situation

if (!$mysqli->query(«SET a=1»)) <
$mysqli->query(«ROLLBACK;»)
printf(«Errormessage: %sn», $mysqli->error);
>

you don’t get an error-message, if the ROLLBACK-Query didn’t failed, too. In order to get the right error-message you have to write:

if (!$mysqli->query(«SET a=1»)) <
printf(«Errormessage: %sn», $mysqli->error);
$mysqli->query(«ROLLBACK;»)
>

I had to set mysqli_report(MYSQLI_REPORT_ALL) at the begin of my script to be able to catch mysqli errors within the catch block of my php code.

Initially, I used the below code to throw and subsequent catch mysqli exceptions

try <
$mysqli = new mysqli ( ‘localhost’ , ‘root’ , ‘pwd’ , ‘db’ );
if ( $mysqli -> connect_errno )
throw new Exception ( $mysqli -> connect_error );

> catch ( Exception $e ) <
echo $e -> getMessage ();
>

I realized the exception was being thrown before the actual throw statement and hence the catch block was not being called .

My current code looks like
mysqli_report ( MYSQLI_REPORT_ALL ) ;
try <
$mysqli = new mysqli ( ‘localhost’ , ‘root’ , ‘pwd’ , ‘db’ );
/* I don’t need to throw the exception, it’s being thrown automatically */

> catch ( Exception $e ) <
echo $e -> getMessage ();
>

This works fine and I ‘m able to trap all mysqli errors

// The idea is the add formated errors information for developers to easier bugs detection.

$myfile = fopen ( «database_log.log» , «r» );
$db = new mysqli ( «localhost» , «root» , «root» , «data» );
if(! $db -> query ( «SELECT» )) <
$timestamp = new DateTime ();
$data_err = » <
»title»: » Select statement error »,
»date_time»: » . $timestamp -> getTimestamp (). «,
»error»:» » . $db -> error . » »
> » ; // Do more information
fwrite ( $myfile , $data_err ); // writing data
>
// In separate file do file read and format it for good visual.

$db -> close ();
fclose ( $myfile );
?>

Please note that the string returned may contain data initially provided by the user, possibly making your code vulnerable to XSS.

So even if you escape everything in your SQL query using mysqli_real_escape_string(), make sure that if you plan to display the string returned by mysqli_error() you run that string through htmlspecialchars().

As far as I can tell the two escape functions don’t escape the same characters, which is why you need both (the first for SQL and the second for HTML/JS).

Hi, you can also use the new mysqli_sql_exception to catch sql errors.
Example:
//set up $mysqli_instance here..
$Select = «SELECT xyz FROM mytable » ;
try <
$res = $mysqli_instance -> query ( $Select );
>catch ( mysqli_sql_exception $e ) <
print «Error Code
» . $e -> getCode ();
print «Error Message
» . $e -> getMessage ();
print «Strack Trace
» . nl2br ( $e -> getTraceAsString ());
>

Источник

string $mysqli->error;

string mysqli_error ( mysqli $link )

mysqli_error(connection);

<?php
$mysqli = new mysqli("localhost", "user1", "datasoft123", "hr");

/* 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();
?>

Errormessage: Unknown system variable 'a'

<?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);
?>

Errormessage: Unknown system variable 'a'

<?php
$con=mysqli_connect("localhost","user1","datasoft123","hr");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

// Perform a query, check for error
if (!mysqli_query($con,"INSERT INTO employees (First_Name) VALUES ('David')"))
  {
  echo("Errorcode: " . mysqli_errno($con));
  }

mysqli_close($con);
?>

Errorcode: 1146

PHP: Tips of the Day

PHP — Generating a random password in PHP

Security warning: rand() is not a cryptographically secure pseudorandom number generator. Look elsewhere for generating a cryptographically secure pseudorandom string in PHP.

Try this (use strlen instead of count, because count on a string is always 1):

function randomPassword() {
    $alphabet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890';
    $pass = array(); //remember to declare $pass as an array
    $alphaLength = strlen($alphabet) - 1; //put the length -1 in cache
    for ($i = 0; $i < 8; $i++) {
        $n = rand(0, $alphaLength);
        $pass[] = $alphabet[$n];
    }
    return implode($pass); //turn the array into a string
}

Ref : https://bit.ly/39BNAs0