How to Fix Database Character Display Issues by Changing Collation to UTF8mb4?

Correcting Database Character Display with UTF8mb4 Collation

A database, initially set up with a Latin collation, is experiencing display issues with Chinese and Japanese characters. This guide outlines the steps to rectify this by switching to the UTF8mb4 collation.

Modifying Database Collation

To change the database's character set and collation:

<code class="language-sql">ALTER DATABASE <database_name> CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;</code>

This command updates the entire database.

Adjusting Table Collation

For situations where only a specific table needs adjustment:

<code class="language-sql">ALTER TABLE <table_name> CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;</code>

Updating Column Collation

To modify the collation of an individual column:

<code class="language-sql">ALTER TABLE <table_name> MODIFY <column_name> VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;</code>

Decoding "utf8mb4_0900_ai_ci"

Let's break down the "utf8mb4_0900_ai_ci" collation:

• utf8mb4: Supports 4-byte Unicode characters (an improvement over utf8).
• 0900: Indicates Unicode version 9.0 and optimized indexing.
• _ai_ci: Specifies accent-insensitive and case-insensitive comparisons.

This ensures correct handling and display of diverse international characters.

Further Resources

For more in-depth information, consult these resources:

• Understanding the differences between utf8_general_ci and utf8_unicode_ci
• Comprehensive guide on changing collations at the database, table, and column levels
• Detailed comparison of utf8_general_ci and utf8_unicode_ci

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