Why is My UTF-8 Data Displaying Incorrectly?

Trouble with UTF-8 Characters: Why Your Data Looks Wrong

Have you encountered strange characters or text that doesn't sort correctly when working with UTF-8? You're not alone. This issue is common and can be caused by various factors.

Causes of UTF-8 Character Encoding Problems

• Incorrect encoding: The data may not be encoded as UTF-8 or the appropriate UTF-8 encoding (e.g., utf8mb4).
• Client-side encoding: The client (e.g., browser, database connection) may not be set to use UTF-8 encoding.
• Database column character set: The database column may not be declared with the correct character set (e.g., utf8mb4).
• HTML encoding: The HTML document may lack the tag.
• Double encoding: Data may have been incorrectly encoded twice, leading to corrupted bytes.

Specific Issues and Troubleshooting

Truncated Text:

• Check that the data bytes are encoded in utf8mb4.
• Ensure the database connection is using utf8mb4 encoding.

Black Diamonds:

• Case 1 (Original Bytes Not in UTF-8)

  • Encode the data in utf8.
  • Set the database connection to utf8mb4.
  • Verify the column's character set (utf8 or utf8mb4).

• Case 2 (Original Bytes in UTF-8)

  • Set the database connection to utf8mb4.
  • Verify the column's character set (utf8 or utf8mb4).

Question Marks:

• Encode the data in utf8mb4.
• Set the database column to utf8mb4 character set.
• Ensure the database connection is using utf8mb4 encoding.

Mojibake:

• Encode the data in UTF-8.
• Set the database connection and column to utf8mb4 encoding.
• Include in the HTML document.

Sorting Issues:

• Select a suitable collation that matches the data's language and sorting requirements.
• Check for double encoding by examining the hex values of the stored data.

Data Recovery

• For truncated or question mark issues, the data is lost and unrecoverable.
• For mojibake or double encoding, data recovery may be possible using the appropriate tools (e.g., iconv).
• For black diamond issues, data recovery is typically impossible.

Best Practices

• Use UTF-8 everywhere (editor, forms, bytes, client, database columns, HTML).
• Use UTF-8mb4 character set and utf8mb4_unicode_520_ci collation.
• Ensure consistency of encodings throughout the system.

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