SQL
Identify and Count Duplicate Records
Locate rows in a table that share identical values in one or more specified columns, useful for data cleaning and ensuring data integrity in your database.
SELECT email, COUNT(*) AS duplicate_count
FROM users
GROUP BY email
HAVING COUNT(*) > 1;
How it works: This query helps identify duplicate entries based on one or more columns. It groups all records by the specified column(s) (here, `email`) and then uses the `HAVING` clause to filter these groups, showing only those where the count of records within the group is greater than one. This is essential for data validation and preventing duplicate entries in critical fields like user emails.