mysqli_set_charset
Sets the character set to be used when sending data from and to the database server.
Parameters
Procedural style only: A mysqli object returned by mysqli_connect() or mysqli_init()
The desired character set.
Return Values
Returns true on success or false on failure.
Errors/Exceptions
If mysqli error reporting is enabled ( MYSQLI_REPORT_ERROR ) and the requested operation fails, a warning is generated. If, in addition, the mode is set to MYSQLI_REPORT_STRICT , a mysqli_sql_exception is thrown instead.
Examples
Example #1 mysqli::set_charset() example
mysqli_report ( MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT );
$mysqli = new mysqli ( «localhost» , «my_user» , «my_password» , «test» );
printf ( «Initial character set: %s\n» , $mysqli -> character_set_name ());
/* change character set to utf8mb4 */
$mysqli -> set_charset ( «utf8mb4» );
printf ( «Current character set: %s\n» , $mysqli -> character_set_name ());
mysqli_report ( MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT );
$link = mysqli_connect ( ‘localhost’ , ‘my_user’ , ‘my_password’ , ‘test’ );
printf ( «Initial character set: %s\n» , mysqli_character_set_name ( $link ));
/* change character set to utf8mb4 */
mysqli_set_charset ( $link , «utf8mb4» );
printf ( «Current character set: %s\n» , mysqli_character_set_name ( $link ));
The above examples will output something similar to:
Initial character set: latin1 Current character set: utf8mb4
Notes
Note:
To use this function on a Windows platform you need MySQL client library version 4.1.11 or above (for MySQL 5.0 you need 5.0.6 or above).
Note:
This is the preferred way to change the charset. Using mysqli_query() to set it (such as SET NAMES utf8 ) is not recommended. See the MySQL character set concepts section for more information.
See Also
- mysqli_character_set_name() — Returns the current character set of the database connection
- mysqli_real_escape_string() — Escapes special characters in a string for use in an SQL statement, taking into account the current charset of the connection
- MySQL character set concepts
- » List of character sets that MySQL supports
User Contributed Notes 5 notes
Setting the charset (it’s really the encoding) like this after setting up your connection:
$connection->set_charset(«utf8mb4»)
FAILS to set the proper collation for the connection:
character_set_client: utf8mb4
character_set_connection: utf8mb4
character_set_database: utf8mb4
character_set_filesystem: binary
character_set_results: utf8mb4
character_set_server: utf8mb4
character_set_system: utf8
collation_connection: utf8mb4_general_ci collation_database: utf8mb4_unicode_ci
collation_server: utf8mb4_unicode_ci
If you use SET NAMES, that works:
$connection->query(«SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci»);
character_set_client: utf8mb4
character_set_connection: utf8mb4
character_set_database: utf8mb4
character_set_filesystem: binary
character_set_results: utf8mb4
character_set_server: utf8mb4
character_set_system: utf8
collation_connection: utf8mb4_unicode_ci collation_database: utf8mb4_unicode_ci
collation_server: utf8mb4_unicode_ci
Please note, that I set the following variables on the server:
Set the following to be: utf8mb4_unicode_ci
character-set-client-handshake = FALSE or 0
skip-character-set-client-handshake = TRUE or 1
So in my case, I had tried changing the collation from utf8mb4_unicode_ci for mysql and had to change it to uft8_general_ci.
mysqli_set_charset( $con, ‘utf8’);
right before I did the SELECT command.
This is my code for reading from db :
$con = mysqli_connect($DB_SERVER, $DB_USER_READER, $DB_PASS_READER, $DB_NAME, $DB_PORT);//this is the unique connection for the selection
mysqli_set_charset( $con, ‘utf8’);
$slct_stmnt = «SELECT «.$SELECT_WHAT.» FROM «.$WHICH_TBL.» WHERE «.$ON_WHAT_CONDITION;
$slct_query = mysqli_query($con, $slct_stmnt);
if ($slct_query==true) //Do your stuff here . . .
>
And it worked like a charm. All the best. The above code can work with reading chineese, russian or arabic or any international language from the database’s table column holding such data.
Although the documentation says that using that function is preferred than using SET NAMES, it is not sufficient in case you use a collation different from the default one:
// That will reset collation_connection to latin1_swedish_ci
// (the default collation for latin1):
$mysqli -> set_charset ( ‘latin1’ );
// You have to execute the following statement *after* mysqli::set_charset()
// in order to get the desired value for collation_connection:
$mysqli -> query ( «SET NAMES latin1 COLLATE latin1_german1_ci» );
To align both the character set (e.g., utf8mb4) AND the collation sequence with the schema (database) settings:
$mysqli = new mysqli ( DB_HOST , DB_USER , DB_PASSWORD , DB_SCHEMA , DB_PORT );
if ( 0 !== $mysqli -> connect_errno )
throw new \ Exception ( $mysqli -> connect_error , $mysqli -> connect_errno );
if ( TRUE !== $mysqli -> set_charset ( ‘utf8mb4’ ) )
throw new \ Exception ( $mysql -> error , $mysqli -> errno );
if ( TRUE !== $mysqli -> query ( ‘SET collation_connection = @@collation_database;’ ) )
throw new \ Exception ( $mysql -> error , $mysqli -> errno );
?>
To confirm:
echo ‘character_set_name: ‘ , $mysqli -> character_set_name (), ‘
‘ , PHP_EOL ;
foreach( $mysqli -> query ( «SHOW VARIABLES LIKE ‘%_connection’;» )-> fetch_all () as $setting )
echo $setting [ 0 ], ‘: ‘ , $setting [ 1 ], ‘
‘ , PHP_EOL ;
?>
will output something like:
character_set_name: utf8mb4
character_set_connection: utf8mb4
collation_connection: utf8mb4_unicode_520_ci
Note that using utf8mb4 with this function may cause this function to return false, depending on the MySQL client library compiled into PHP. If the client library is older than the introduction of utf8mb4, then PHP’s call of the libraries ‘mysql_set_character_set’ will return an error because it won’t recognise that character set.
The only way you will know there’s an error is by checking the return value, because PHP warnings are not emitted by this function.
mysqli_error will return something like:
«Can’t initialize character set utf8mb4 (path: /usr/share/mysql/charsets/)»
(I don’t think the directory has anything to do with it; I think the utf8mb4 vs utf8 distinction is handled internally)
A workaround is to recall with utf8, then do a ‘SET NAMES’ query with utf8mb4.
If your MySQL server is configured to use utf8 by default, then you may not notice any of this until you get obscure bugs. It seems it will still save into the database correctly in terms of bytes. However, you may get «Data too long for column» errors if you are truncating strings to fit fields, because from MySQL’s point of view during the length check every 4-byte character will actually be multiple individual characters. This caused me hours of debugging.
Кодировка символов и экранирование символов
Кодировка символов должна быть чётко определена, поскольку влияет на каждое действие, в том числе на действия с последствиями для безопасности. Например, механизмы экранирования (такие как mysqli_real_escape_string() для mysqli и PDO::quote() для PDO_MySQL) зависят от этих настроек. Важно понимать, что эти функции не используют кодировку символов определённую в запросе, так например, следующие запросы не будут влиять на поведение этих функций:
Пример #1 Проблемы установки кодировки символов с помощью SQL
$mysqli = new mysqli ( «localhost» , «my_user» , «my_password» , «world» );
// Этот запрос не влияет на поведение $mysqli->real_escape_string();
$mysqli -> query ( «SET NAMES utf8mb4» );
// И этот не влияет на $mysqli->real_escape_string();
$mysqli -> query ( «SET CHARACTER SET utf8mb4» );
// но вот этот запрос повлияет на поведение $mysqli->real_escape_string();
$mysqli -> set_charset ( ‘utf8mb4’ );
// а этот НЕ повлияет, потому что нельзя использовать «-»
$mysqli -> set_charset ( ‘UTF-8’ ); // (utf8mb4, а не UTF-8)
?>
Примеры ниже демонстрируют, как правильно изменять кодировку символов во время выполнения, используя каждый из API.
Замечание: Возможная путаница с UTF-8
Поскольку имена кодировок символов в MySQL не содержат тире/дефис, строка «utf8» применяется в MySQL для установки кодировки UTF-8 (до 3 байт в кодировке Unicode UTF-8). Строка «UTF-8» неприемлема и выбросит ошибку при установке кодировки символов.
Пример #2 Пример установки кодировки символов: mysqli
$mysqli = new mysqli ( «localhost» , «my_user» , «my_password» , «world» );
echo ‘Первоначальная кодировка: ‘ . $mysqli -> character_set_name () . «\n» ;
if (! $mysqli -> set_charset ( ‘utf8mb4’ )) printf ( «Ошибка загрузки кодировки utf8mb4: %s\n» , $mysqli -> error );
exit;
>
echo ‘Ваша текущая кодировка: ‘ . $mysqli -> character_set_name () . «\n» ;
?>
Пример #3 Пример установки кодировки символов: pdo_mysql