How Can I Detect and Identify Hidden Non-ASCII Characters in My MySQL Database?

Uncovering Hidden Non-ASCII Characters in MySQL

When working with MySQL databases that have data imported from sources like Excel, it's not uncommon to encounter non-ASCII characters and hidden carriage returns or line feeds. Identifying these records is crucial for data accuracy and readability.

MySQL's robust character set management offers a solution to this challenge. The CONVERT(col USING charset) function plays a vital role in revealing unconvertable characters. By comparing the original text with the converted version, we can identify the non-ASCII characters.

SELECT whatever
  FROM tableName 
 WHERE columnToCheck <> CONVERT(columnToCheck USING ASCII)

The unconvertable characters are replaced with placeholders using the CONVERT function, resulting in an inequality between the converted and unconverted text.

For instance, if you wish to determine characters that might display incorrectly in the 1257 code page (used in Lithuanian, Latvian, and Estonian), you can use:

CONVERT(columnToCheck USING cp1257)

By utilizing various character sets with the CONVERT function, MySQL empowers you to pinpoint non-ASCII characters and ensure data integrity within your database.

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