Question

Say I have a table like this:

model_id | object_id | date_modified
1        | 123       | NULL
1        | 123       | 2012-12-11 16:55:21
1        | 456       | 2012-12-11 16:52:21
1        | 789       | NULL

I want to return the object_ids that have not been modified. Here’s what I’ve tried thus far:

SELECT object_id from Table WHERE date_modified IS NULL

This returns 123 and 789, I only want 789.

SELECT DISTINCT object_id from Table WHERE date_modified IS NULL

This also returns 123 and 789 as the DISTINCT clause is applied after the WHERE filters the results.

Is there a way to achieve this with a single query or should I just return a list of distinct object_ids and loop through and filter programmatically?

Answer 1

SELECT object_id from Table GROUP BY object_id HAVING MAX(date_modified) IS NULL