Question

I was wondering if there is a way to filter rows which have a corresponding row in a different table using JOIN operation, or perhaps using any other method which does not involve sub queries.

Here is the only thing I could come up with, however it uses subqueries and I am afraid that it could become quite slow when dealing with very large tables.

SELECT * FROM `reports` as R WHERE (
    SELECT COUNT(*) 
    FROM `report_deletes` as RD 
    WHERE 
        RD.report_id = R.id AND
        RD.user_id = 1
) = 0;

Answer 1

Use a left join and check for NULL:

SELECT r.* 
FROM reports r 
LEFT JOIN report_deletes rd on r.id = rd.report_id and rd.user_id = 1 
WHERE rd.report_id IS NULL