Find Duplicate Email Records in MySQL with Regex Filter
Detect duplicate valid email addresses in MySQL using GROUP BY with REGEXP validation. SQL deduplication query examples.
The Regex Pattern
Regex pattern
^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$Use this pattern with MySQL's REGEXP operator.
MySQL SQL Example
-- Use GROUP BY with HAVING COUNT > 1 combined with REGEXP email validation to find duplicate valid email records
SELECT *
FROM your_table
WHERE your_column REGEXP '^[a-zA-Z0-9._%+\\-]+@[a-zA-Z0-9.\\-]+\\.[a-zA-Z]{2,}$';How This Works
Use GROUP BY with HAVING COUNT > 1 combined with REGEXP email validation to find duplicate valid email records. 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 duplicate detection — it avoids loading data into application memory just to filter it with a regex.
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