Help Center> Relational Database Service> FAQs> Database Parameter Modification> How Do I Ensure that the Character Set of an RDS MySQL Database Is Correct?
View PDF

How Do I Ensure that the Character Set of an RDS MySQL Database Is Correct?

UTF-8 supports 4 byte characters, while MySQL utf8 supports only 3 byte characters. Emojis, uncommon Chinese characters, and newly added Unicode characters cannot be stored using MySQL utf8 character set. MySQL released the utf8mb4 character set in 2010 and added the utf8mb4 code since 5.5.3 to compatible with the 4-byte unicode. You only need to change utf8 to utf8mb4. No other conversion is required.

HUAWEI CLOUD Data Admin Service (DAS) is a professional database management tool. You can view the database and system character sets through the DAS console.

Procedure

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click Service List. Under Database, click Relational Database Service. The RDS console is displayed.
  4. On the Instance Management page, locate the target DB instance and click Log In in the Operation column.

    Alternatively, click the target DB instance on the Instance Management page. On the displayed Basic Information page, click Log In in the upper right corner of the page.

  5. On the displayed login page, enter the correct username and password and click Log In.
  6. On the top menu bar, choose SQL Operation > SQL Window.
  7. Run the following SQL statement in the SQL window to view the database character set:

    show variables like '%character%';

    Figure 1 SQL execution result

  8. Run the following SQL statement in the SQL window to view the database coding:

    show variables like 'collation%';

    Figure 2 SQL execution result

  9. Change the character set to utf8mb4.

    1. Run the following SQL statement to change the database character sets.

      ALTER DATABASE DATABASE_NAME DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

    2. Run the following SQL statement to change the table character sets.
      ALTER TABLE TABLE_NAME DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

      The SQL statement just changes the character sets of tables. The character sets of fields in the tables are not changed.

    3. Run the following SQL statement to change all the field character sets in tables:

      ALTER TABLE TABLE_NAME CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

    • character_set_client, character_set_connection, and character_set_results are the settings of the client.
    • character_set_system, character_set_server, and character_set_database are the settings of the server.
    • The priorities of the parameters on the server are as follows: character_set_database > character_set_server > character_set_system.
    • To change character_set_server and set names, see How Do I Use the utf8mb4 Character Set to Store Emoji in an RDS for MySQL DB Instance?