Identify and Remove Duplicate Rows (Keeping One)

-- 1. Identify duplicates:
SELECT
    column1, column2, COUNT(*)
FROM
    your_table
GROUP BY
    column1, column2
HAVING
    COUNT(*) > 1;

-- 2. Delete duplicates, keeping the one with the minimum ID (example for MySQL/PostgreSQL/SQL Server):
DELETE FROM
    your_table
WHERE
    id NOT IN (
        SELECT
            MIN(id)
        FROM
            your_table
        GROUP BY
            column1, column2
    );

How it works: This snippet provides a two-step approach to handle duplicate records in your database. The first query helps you identify which combinations of `column1` and `column2` have more than one entry, flagging potential duplicates. The second query then safely deletes all duplicate rows, ensuring that at least one (specifically, the one with the minimum `id` in this example) is kept. This is crucial for maintaining data uniqueness and integrity, especially after data imports or during clean-up operations.