Data Storage and Access

This topic specifically talks about UTF-8 and considerations for using it with a database. If you want more information about using databases in PHP then checkout this topic.

Storing Data in a MySQL Database:

• Specify the utf8mb4 character set on all tables and text columns in your database. This makes MySQL physically store and retrieve values encoded natively in UTF-8.

MySQL will implicitly use utf8mb4 encoding if a utf8mb4_* collation is specified (without any explicit character set).

• Older versions of MySQL (< 5.5.3) do not support utf8mb4 so you’ll be forced to use utf8, which only supports a subset of Unicode characters.

Accessing Data in a MySQL Database:

• In your application code (e.g. PHP), in whatever DB access method you use, you’ll need to set the connection charset to utf8mb4. This way, MySQL does no conversion from its native UTF-8 when it hands data off to your application and vice versa.
• Some drivers provide their own mechanism for configuring the connection character set, which both updates its own internal state and informs MySQL of the encoding to be used on the connection. This is usually the preferred approach.

For Example (The same consideration regarding utf8mb4/utf8 applies as above):

- If you're using the [PDO][1] abstraction layer with PHP ≥ 5.3.6, you can specify `charset` in the [DSN][2]:

      $handle = new PDO('mysql:charset=utf8mb4');

- If you're using [mysqli][3], you can call [`set_charset()`][4]:

      $conn = mysqli_connect('localhost', 'my_user', 'my_password', 'my_db');

      $conn->set_charset('utf8mb4');        // object oriented style
      mysqli_set_charset($conn, 'utf8mb4'); // procedural style

- If you're stuck with plain [mysql][5] but happen to be running PHP ≥ 5.2.3, you can call [`mysql_set_charset`][6].

      $conn = mysql_connect('localhost', 'my_user', 'my_password');

      $conn->set_charset('utf8mb4');       // object oriented style
      mysql_set_charset($conn, 'utf8mb4'); // procedural style

- If the database driver does not provide its own mechanism for setting the connection character set, you may have to issue a query to tell MySQL how your application expects data on the connection to be encoded: [`SET NAMES 'utf8mb4'`][7].