Use `DISTINCT` to return unique rows
Use `GROUP BY` to group identical rows and keep one result
Use `ROW_NUMBER()` with a CTE or subquery to identify duplicates and delete extra rows
Use `RANK()` or `DENSE_RANK()` when duplicates need to be handled by priority rules
Use `DELETE` with a self-join to remove repeated rows
Use `EXISTS` or `NOT EXISTS` to keep only the first matching row
Use a temporary table to store unique rows, then replace the original table
Use `UNION` instead of `UNION ALL` to eliminate duplicate result rows
Add a `UNIQUE` constraint or index to prevent future duplicates
Use `SELECT DISTINCT ON` in databases that support it, such as PostgreSQL