How Can I Solve UTF-8 Encoding Problems in My Database and Application?

Addressing UTF-8 Character Encoding Woes

In your quest to implement UTF-8, you have encountered various complexities, hindering the accurate storage and display of non-English characters. This article delves into the root causes of these issues and provides solutions to restore your data and code integrity.

Best Practices

For optimal UTF-8 handling, it's crucial to adopt the recommended settings:

• Utilize CHARACTER SET utf8mb4 and COLLATION utf8mb4_unicode_520_ci.
• Treat UTF-8 as a superset to utf8, encompassing 4-byte UTF-8 codes (e.g., Emoji, certain Chinese characters).

Encoding Consistency

Throughout your workflow, maintain UTF-8 encoding:

• Configure your text editor and website forms accordingly.
• Ensure that input data and stored database columns adhere to UTF-8 formats.
• Establish UTF-8 encoding in your database connections and client-server interactions.

Data Verification

When reviewing stored data, rely on reliable methods to assess its integrity:

• Perform a SELECT query with HEX conversion to validate character encodings.
• Expect hex values in the ranges specified for the character sets and collations in use.

Problem Analysis and Resolution

Truncated Text (Se for Señor)

• Verify the correct encoding (utf8mb4) of data being stored.
• Ensure UTF-8 encoding is active during both read and write operations.

Black Diamonds with Question Marks (Se�or)

Case 1 (Original Bytes Not UTF-8)

• Encode data in utf8 format.
• Use a UTF-8 connection (or SET NAMES) for INSERT and SELECT operations.
• Confirm that the database column is CHARACTER SET utf8.

Case 2 (Original Bytes Were UTF-8)

• Use a UTF-8 connection (or SET NAMES) for SELECT operations.
• Ensure that the database column is CHARACTER SET utf8.

Question Marks (Regular, Not Black Diamonds) (Se?or)

• Encode data as utf8/utf8mb4.
• Set the database column to CHARACTER SET utf8 (or utf8mb4).
• Verify UTF-8 encoding during data retrieval.

Mojibake (Señor)

• Ensure UTF-8 encoding of stored data.
• Establish utf8 or utf8mb4 encoding for database connections and SELECT statements.
• Configure MySQL with CHARACTER SET utf8 (or utf8mb4) for the affected columns.
• Include the meta charset=UTF-8 in HTML code.

Sorting Issues

Incorrect sorting can result from unsuitable collations, double encoding, or a lack of a suitable collation. Verify the appropriate collation usage and resolve any double encoding.

Data Recovery

Unfortunately, truncated or lost data may not be recoverable.

For Mojibake / Double Encoding:

• Refer to the provided fixes for specific problem scenarios.

For Black Diamonds:

• Apply the recommended fixes.

Additional Resources

• Illegal mix of collations: https://dev.mysql.com/doc/refman/5.8/en/charset-connection.html#charset-connection-ill-mix

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