MySQLdata validation

Find Invalid Usernames in MySQL with REGEXP

Use MySQL REGEXP to detect usernames with special characters or wrong length in your users table. SQL audit examples.

The Regex Pattern

Regex pattern

[^a-zA-Z0-9_]

Use this pattern with MySQL's REGEXP operator.

MySQL SQL Example

-- Audit a MySQL users table to find all usernames that do not conform to alphanumeric-underscore format policy
SELECT *
FROM your_table
WHERE your_column REGEXP '[^a-zA-Z0-9_]';

How This Works

Audit a MySQL users table to find all usernames that do not conform to alphanumeric-underscore format policy. The regex pattern is used with MySQL's REGEXP operator to filter rows at the database level.

Using regex directly in SQL is efficient for use cases like data validation — it avoids loading data into application memory just to filter it with a regex.

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