Php mysqli query exception



mysqli::$error

(PHP 5, PHP 7, PHP 8)

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: %s\n» , $mysqli -> connect_error );
exit();
>

if (! $mysqli -> query ( «SET a=1» )) <
printf ( «Error message: %s\n» , $mysqli -> error );
>

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

= mysqli_connect ( «localhost» , «my_user» , «my_password» , «world» );

/* check connection */
if ( mysqli_connect_errno ()) <
printf ( «Connect failed: %s\n» , mysqli_connect_error ());
exit();
>

if (! mysqli_query ( $link , «SET a=1» )) <
printf ( «Error message: %s\n» , 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: %s\n» , $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: %s\n» , $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:\data\WorkSites\1framework5\tests\dbtest.php(29): database->getString(‘SELECT XXname F. ‘)
#2 c:\PHP\includes\simpletest\runner.php(58): testOfDB->testGetVal()
#3 c:\PHP\includes\simpletest\runner.php(96): SimpleInvoker->invoke(‘testGetVal’)
#4 c:\PHP\includes\simpletest\runner.php(125): SimpleInvokerDecorator->invoke(‘testGetVal’)
#5 c:\PHP\includes\simpletest\runner.php(183): SimpleErrorTrappingInvoker->invoke(‘testGetVal’)
#6 c:\PHP\includes\simpletest\simple_test.php(90): SimpleRunner->run()
#7 c:\PHP\includes\simpletest\simple_test.php(498): SimpleTestCase->run(Object(HtmlReporter))
#8 c:\PHP\includes\simpletest\simple_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: %s\n», $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: %s\n», $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.

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$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

mysqli::query

(PHP 5, PHP 7, PHP 8)

mysqli::query — mysqli_query — Выполняет запрос к базе данных

Описание

Выполняет запрос query к базе данных.

Для не DML-запросов (не INSERT, UPDATE или DELETE), эта функция равносильна вызову функции mysqli_real_query() , а затем mysqli_use_result() или mysqli_store_result() .

В случае, если длина выражения, которое передаётся в mysqli_query() , больше, чем max_allowed_packet сервера, возвращаемые коды ошибки могут различаться в зависимости от используемого драйвера. А это может быть либо родной MySQL драйвер ( mysqlnd ), либо клиентская библиотека MySQL ( libmysqlclient ). Поведение функции будет следующим:

mysqlnd на платформе Linux возвращает код ошибки 1153. Сообщение об ошибке означает размер пакета превышает max_allowed_packet байт .

mysqlnd на платформе Windows возвращает код ошибки 2006. Это сообщение об ошибке означает отказ сервера .

libmysqlclient на всех платформах возвращает код ошибки 2006. Это сообщение об ошибке означает отказ сервера .

Список параметров

Только для процедурного стиля: объект mysqli , полученный с помощью mysqli_connect() или mysqli_init() .

Предупреждение безопасности: SQL-инъекция

Если запрос содержит какие-либо входные переменные, вместо этого следует использовать подготавливаемые запросы. В качестве альтернативы данные должны быть правильно отформатированы и все строки должны быть экранированы с помощью функции mysqli_real_escape_string() .

Режим результата может быть одной из 3 констант, указывающих, как результат будет возвращён сервером MySQL.

MYSQLI_STORE_RESULT (по умолчанию) — возвращает объект mysqli_result с буферизованным набором результатов.

MYSQLI_USE_RESULT — возвращает объект mysqli_result с небуферизованным набором результатов. Пока есть отложенные записи, ожидающие выборки, линия соединения будет занята и все последующие вызовы будут возвращать ошибку Commands out of sync . Чтобы избежать ошибки, все записи должны быть получены с сервера или набор результатов должен быть отброшен путём вызова mysqli_free_result() .

MYSQLI_ASYNC (доступно с mysqlnd) — запрос выполняется асинхронно, набор результатов сразу не возвращается. Затем используется mysqli_poll() для получения результатов по этим запросам. Используется в сочетании с константой MYSQLI_STORE_RESULT или MYSQLI_USE_RESULT .

Возвращаемые значения

Возвращает false в случае возникновения ошибки. В случае успешного выполнения запросов, которые создают набор результатов, таких как SELECT, SHOW, DESCRIBE или EXPLAIN , mysqli_query() вернёт объект mysqli_result . Для остальных успешных запросов mysqli_query() вернёт true .

Примеры

Пример #1 Пример использования mysqli::query()

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

/* Создание таблицы, не возвращает набор результатов */
$mysqli -> query ( «CREATE TEMPORARY TABLE myCity LIKE City» );
printf ( «Таблица myCity создана.\n» );

/* Запросы SELECT, возвращают набор результатов */
$result = $mysqli -> query ( «SELECT Name FROM City LIMIT 10» );
printf ( «Запрос SELECT вернул %d строк.\n» , $result -> num_rows );

/* Если нужно извлечь большой объем данных, используем MYSQLI_USE_RESULT */
$result = $mysqli -> query ( «SELECT * FROM City» , MYSQLI_USE_RESULT );

/* Важно заметить, что мы не можем вызывать функции, которые взаимодействуют
с сервером, пока не закроем набор результатов. Все подобные вызовы
будут вызывать ошибку ‘out of sync’ */
$mysqli -> query ( «SET @a:=’this will not work'» );

( MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT );
$link = mysqli_connect ( «localhost» , «my_user» , «my_password» , «world» );

/* Создание таблицы, не возвращает набор результатов */
mysqli_query ( $link , «CREATE TEMPORARY TABLE myCity LIKE City» );
printf ( «Таблица myCity создана.\n» );

/* Запросы SELECT, возвращают набор результатов */
$result = mysqli_query ( $link , «SELECT Name FROM City LIMIT 10» );
printf ( «Запрос SELECT вернул %d строк.\n» , mysqli_num_rows ( $result ));

/* Если нужно извлечь большой объем данных, используем MYSQLI_USE_RESULT */
$result = mysqli_query ( $link , «SELECT * FROM City» , MYSQLI_USE_RESULT );

/* Важно заметить, что мы не можем вызывать функции, которые взаимодействуют
с сервером, пока не закроем набор результатов. Все подобные вызовы
будут вызывать ошибку ‘out of sync’ */
mysqli_query ( $link , «SET @a:=’this will not work'» );

Результат выполнения данных примеров:

Смотрите также

  • mysqli_real_query() — Выполнение SQL запроса
  • mysqli_multi_query() — Выполняет один или несколько запросов к базе данных
  • mysqli_prepare() — Подготавливает SQL выражение к выполнению
  • mysqli_free_result() — Освобождает память, занятую результатами запроса

User Contributed Notes 21 notes

This may or may not be obvious to people but perhaps it will help someone.

When running joins in SQL you may encounter a problem if you are trying to pull two columns with the same name. mysqli returns the last in the query when called by name. So to get what you need you can use an alias.

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Below I am trying to join a user id with a user role. in the first table (tbl_usr), role is a number and in the second is a text name (tbl_memrole is a lookup table). If I call them both as role I get the text as it is the last «role» in the query. If I use an alias then I get both as desired as shown below.

= «SELECT a.uid, a.role AS roleid, b.role,
FROM tbl_usr a
INNER JOIN tbl_memrole b
ON a.role = b.id
» ;

if ( $result = $mysqli -> query ( $sql )) <
while( $obj = $result -> fetch_object ()) <
$line .= $obj -> uid ;
$line .= $obj -> role ;
$line .= $obj -> roleid ;
>
>
$result -> close ();
unset( $obj );
unset( $sql );
unset( $query );

?>
In this situation I guess I could have just renamed the role column in the first table roleid and that would have taken care of it, but it was a learning experience.

The cryptic «Couldn’t fetch mysqli» error message can mean any number of things, including:

1. You’re trying to use a database object that you’ve already closed (as noted by ceo at l-i-e dot com). Reopen your database connection, or find the call to ( $db ); ?> or -> close (); ?> and remove it.
2. Your MySQLi object has been serialized and unserialized for some reason. Define a wakeup function to re-create your database connection. http://php.net/__wakeup
3. Something besides you closed your mysqli connection (in particular, see http://bugs.php.net/bug.php?id=33772)
4. You mixed OOP and functional calls to the database object. (So, you have -> query () ?> in the same program as ( $db ) ?> ).

When calling multiple stored procedures, you can run into the following error: «Commands out of sync; you can’t run this command now».
This can happen even when using the close() function on the result object between calls.
To fix the problem, remember to call the next_result() function on the mysqli object after each stored procedure call. See example below:

// New Connection
$db = new mysqli ( ‘localhost’ , ‘user’ , ‘pass’ , ‘database’ );

// Check for errors
if( mysqli_connect_errno ()) <
echo mysqli_connect_error ();
>

// 1st Query
$result = $db -> query ( «call getUsers()» );
if( $result ) <
// Cycle through results
while ( $row = $result -> fetch_object ()) <
$user_arr [] = $row ;
>
// Free result set
$result -> close ();
$db -> next_result ();
>

// 2nd Query
$result = $db -> query ( «call getGroups()» );
if( $result ) <
// Cycle through results
while ( $row = $result -> fetch_object ()) <
$group_arr [] = $row ;
>
// Free result set
$result -> close ();
$db -> next_result ();
>
else echo( $db -> error );

// Close connection
$db -> close ();
?>

Here is an example of a clean query into a html table

while ( $row = $myquery -> fetch_assoc ()) < ?>

> ?>

First Name Last Name City
echo $row [ «firstname» ]; ?> echo $row [ «lastname» ]; ?> echo $row [ «city» ]; ?>

Use mysqli_query to call a stored procedure that returns a result set.

Here is a short example:

= new mysqli ( DBURI , DBUSER , DBPASS , DBNAME );
if ( mysqli_connect_errno ())
<
printf ( «Connection failed: %s\n» , mysqli_connect_error ());
exit();
>

$SQL = «CALL my_procedure( $something )» ;
if ( ( $result = $mysqli -> query ( $SQL ))=== false )
<
printf ( «Invalid query: %s\nWhole query: %s\n» , $mysqli -> error , $SQL );
exit();
>

while ( $myrow = $result -> fetch_array ( MYSQLI_ASSOC ))
<
$aValue []= $myrow [ «a» ];
$bValue []= $myrow [ «b» ];
>
$result -> close ();
$mysqli -> close ();
?>
I hope this saves someone some time.

I like to save the query itself in a log file, so that I don’t have to worry about whether the site is live.

For example, I might have a global function:

function UpdateLog ( $string , $logfile ) <
$fh = fopen ( $logfile , ‘a’ );
$fwrite ( $fh , strftime ( ‘%F %T %z’ ). » » . $string . «\n» ;
fclose ( $fh );
>
?>

Then in my mysql function error trapper, something like this:

= «Database error in [page].php / » ;
$error_msg .= mysqli_error ( $link ). » / » ;
$error_msg .= $query ;
UpdateLog ( $error_msg , DB_ERROR_LOG_FILE );
?>

I also include the remote IP, user agent, etc., but I left it out of these code samples. And have it e-mail me when an error is caught, too.

Translation:
«Couldn’t fetch mysqli»

You closed your connection and are trying to use it again.

It has taken me DAYS to figure out what this obscure error message means.

When building apps, i like to see the whole statement when if fails.
= «SELECT somecolumn FROM sometable» ; //some instruction
$r = mysqli_query ( $DBlink , $q ) or die( mysqli_error ( $DBlink ). » Q=» . $q );
?>
If theres an error (like my numerous typing mistakes) this shows the entire instruction.
Good for development (not so good on production servers — simply find and replace when finished: $r=mysqli_query($DBlink,$q); )

Hope it helps. Jon

Calling Stored Procedures

Beeners’ note/example will not work. Use mysqli_multi_query() to call a Stored Procedure. SP’s have a second result-set which contains the status: ‘OK’ or ‘ERR’. Using mysqli_query will not work, as there are multiple results.

= «CALL SomeSP(‘params’)» ;
if(! mysqli_multi_query ( $sqlLink , $sQuery )) <
// your error handler
>
$sqlResult = mysqli_store_result ( $sqlLink );

if( mysqli_more_results ( $this -> sqlLink )) //Catch ‘OK’/’ERR’
while( mysqli_next_result ( $this -> sqlLink ));
?>

You will have to rewrite/expand this a bit for more usability of course, but it’s just an example.

For those using with replication enabled on their servers, add a mysqli_select_db() statement before any data modification queries. MySQL replication does not handle statements with db.table the same and will not replicate to the slaves if a scheme is not selected before.

mysqli::query() can only execute one SQL statement.

Use mysqli::multi_query() when you want to run multiple SQL statements within one query.

Use difference collation/character for connect, result.
You can set the collation before your query.

E.g. want to set the collation to utf8_general_ci
you can send the query «SET NAMES ‘utf8′» first

=new mysqli ( ‘localhost’ , ‘root’ , ‘password’ , ‘test’ );
$mysqli -> query ( «SET NAMES ‘utf8′» );
$q = $mysqli -> query ( «select * from test» );
while( $r = $q -> fetch_assoc ()) <
print_r ( $r );
>
?>

There are many variables about character settings.
By running sql command, SHOW VARIABLES LIKE ‘char%’;
There are some variables control the character usage.

Also SET NAMES can repalce with one or some settings like SET character_set_results=’utf8′;

Hi, i created function that add a new table using array , i work with it on my projects .
/* this function was learned from PHP.net */
function array_keys_exist (& $key ,array & $array ) <
$keys = split ( «\|» , $key );
foreach( $keys as $key_s ) <
if( array_key_exists ( $key_s , $array )) return true ;
>
return false ;
>
/*and this is my function */
array_create_table (array & $array ) <
if( is_array ( $array )) <
$key = «table|rows|values» ;
$info = «» ;
if( array_keys_exist ( $key , $array )) <
if( is_array ( $array [ «rows» ]) and is_array ( $array [ «values» ]) )<

if( count ( $array [ «rows» ]) == count ( $array [ «values» ])) <
for( $i = 0 ; $i count ( $array [ «rows» ]); $i ++) <
$info = $info . » » . $array [ «rows» ][ $i ]. » » . $array [ «values» ][ $i ]. » NOT NULL » ;
if( $i count ( $array [ «rows» ])- 1 ) $info = $info . «,» ;
>
$query = «CREATE TABLE » . $this -> private_tables_name . $array [ «table» ]. » » ;
$query .= «( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, » . $info . » )» ;
return $query ;
>
>
>else return «Error» ;
>
>

/* the use is simple */
$database = new database (); // connection to database i used mysqli .
$array = array( «table» => «MRO» , «rows» =>array( «name» , «username» ) , «values» => array( «VARCHAR (50) » , » VARCHAR (50) » ) );

$query = array_create_table ( $array ); // convert and create the query .
if( $database -> query ( $query )) echo «Work» ; else echo «Error» ; // result : work

Building inserts can be annoying. This helper function inserts an array into a table, using the key names as column names:

private function store_array (& $data , $table , $mysqli )
<
$cols = implode ( ‘,’ , array_keys ( $data ));
foreach ( array_values ( $data ) as $value )
<
isset( $vals ) ? $vals .= ‘,’ : $vals = » ;
$vals .= ‘\» . $this -> mysql -> real_escape_string ( $value ). ‘\» ;
>
$mysqli -> real_query ( ‘INSERT INTO ‘ . $table . ‘ (‘ . $cols . ‘) VALUES (‘ . $vals . ‘)’ );
>
?>

Adapt it to your specific needs.

or you could just extend the class.
in my case i already had a wraper for the db so something like this was easy :

public function free($result) <

just tried it and it works like a charm 😉

This Is A Secure Way To Use mysqli::query
———————————————————
function secured_query ( $sql )
<
$connection = new mysqli ( $host , $username , $password , $name );

if ( $connection -> connect_error )
die( «Secured» );

$result = $connection -> query ( $sql );
if( $result == FALSE )
die( «Secured» );

$connection -> close ();
return $result ;
>
/*
$host —> DataBase IP Address
$username —> DataBase Username
$password —> DataBase Password
$name —> DataBase Name
*/
?>

Recently I had puzzling problem when performing DML queries, update in particular, each time a update query is called and then there are some more queries to follow this error will show on the page and go in the error_log:
«Fatal error: Exception thrown without a stack frame in Unknown on line 0»

The strange thing is that all queries go through just fine so it didn’t make much sense:

$update = mysqli_query($connection, $query_string);
if(!$update) <
echo ‘Houston we have a problem ‘.mysqli_error($connection);
exit;
>

In the above example «$update» is «true», mysqli_error() is empty and of course the update operation goes through, however the nasty super cryptic error appears on the page.
What makes even less sense to me is how I fixed it — just called «mysqli_free_result» after the update query and the problem was gone, however because mysqli_free_result is not supposed to be called after DML queries (to free what, a boolean? lol) it needs to be wrapped in a try catch block:

try <
mysqli_free_result($update);
>catch (Exception $e) <
//do nothing
>

So, I don’t know why but it seems that when DML queries are responsible for:
«Fatal error: Exception thrown without a stack frame in Unknown on line 0»
calling «mysqli_free_result» after the query seems to be fixing the issue

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