Identify and Delete Duplicate Records (Keep One)

WITH CTE AS (
    SELECT 
        column1, column2, 
        ROW_NUMBER() OVER (PARTITION BY column1, column2 ORDER BY id) as rn
    FROM 
        your_table
)
DELETE FROM CTE WHERE rn > 1;

How it works: This SQL query provides a method to identify and delete duplicate records from a table, ensuring only one unique entry remains. It uses a Common Table Expression (CTE) and the `ROW_NUMBER()` window function. `PARTITION BY column1, column2` groups rows by the columns that define a 'duplicate', and `ORDER BY id` (assuming `id` is a primary key) determines which row within each group is kept. Rows with `rn > 1` are duplicates and are subsequently deleted, leaving only the first occurrence.