Character sets

Ideally a proper character set will be set at the server level, and doing this is described within the » Character Set Configuration section of the MySQL Server manual. Alternatively, each MySQL API offers a method to set the character set at runtime.

Caution

The character set and character escaping

The character set should be understood and defined, as it has an affect on every action, and includes security implications. For example, the escaping mechanism (e.g., mysqli_real_escape_string() for mysqli, mysql_real_escape_string() for mysql, and PDO::quote() for PDO_MySQL) will adhere to this setting. It is important to realize that these functions will not use the character set that is defined with a query, so for example the following will not have an effect on them:

Example #1 Problems with setting the character set with SQL

  <?php

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

 // Will NOT affect $mysqli->real_escape_string();
 $mysqli -> query ( "SET NAMES utf8" );

 // Will NOT affect $mysqli->real_escape_string();
 $mysqli -> query ( "SET CHARACTER SET utf8" );

 // But, this will affect $mysqli->real_escape_string();
 $mysqli -> set_charset ( 'utf8' );

 // But, this will NOT affect it (utf-8 vs utf8) -- don't use dashes here
 $mysqli -> set_charset ( 'utf-8' );

 ?>

Below are examples that demonstrate how to properly alter the character set at runtime using each API.

Note: Possible UTF-8 confusion

Because character set names in MySQL do not contain dashes, the string "utf8" is valid in MySQL to set the character set to UTF-8. The string "utf-8" is not valid, as using "utf-8" will fail to change the character set.

Example #2 Setting the character set example: mysqli

  <?php
$mysqli  = new  mysqli ( "localhost" ,  "my_user" ,  "my_password" ,  "world" );

 printf ( "Initial character set: %s\n" ,  $mysqli -> character_set_name ());

if (! $mysqli -> set_charset ( 'utf8' )) {
     printf ( "Error loading character set utf8: %s\n" ,  $mysqli -> error );
    exit;
}

echo  "New character set information:\n" ;
 print_r (  $mysqli -> get_charset () );

 ?>

Example #3 Setting the character set example: pdo_mysql

Note: This only works as of PHP 5.3.6.

  <?php
$pdo  = new  PDO ( "mysql:host=localhost;dbname=world;charset=utf8" ,  'my_user' ,  'my_pass' );
 ?>

Example #4 Setting the character set example: mysql

  <?php
$conn  =  mysql_connect ( "localhost" ,  "my_user" ,  "my_pass" );
 $db    =  mysql_select_db ( "world" );

echo  'Initial character set: '  .   mysql_client_encoding ( $conn ) .  "\n" ;

if (! mysql_set_charset ( 'utf8' ,  $conn )) {
    echo  "Error: Unable to set the character set.\n" ;
    exit;
}

echo  'Your current character set is: '  .   mysql_client_encoding ( $conn );
 ?>

用户评论:

[#1] go at NOSPAMME dot quidera dot com [2012-08-30 17:11:59]

If none of the character set alterations work and the data is valid UTF8 and is garbled when saved in mysql. Then your table is not supporting UTF8 and likely is Latin1 or something else. So you will need to update you table, in the case of MySQL do the following:

ALTER TABLE <table_name> CONVERT TO CHARACTER SET utf8;