Question

Ok, so I have an organization id column named org_id in several databases.

I am writing a search function that will query two of these databases, and look for all org_id’s associated with a value in these two tables.

I ONLY want to ultimately have the org_id’s that correspond with the values I am querying for in EACH table.

For example:

Say I have an org_id of 3 that is in the tables cult_xref and cat_xref, which are both associated with an organization table, which isn’t really relevant for this. I want to ONLY pull those org_id’s which are in BOTH tables cult_xref and cat_xref, based on values I put into those tables, say 2 and 6 respectively.

So:

cult_xref

org_id     | cult_id
3          | 2
4          | 2
3          | 5

and

cat_xref

org_id     | cat_id
3          | 6
3          | 1
7          | 6

I would only want to pull the org_id’s that fulfill cult_id[‘2’] and cat_id[‘6’] at the SAME TIME.

Answer 1

In SQL, this is called a JOIN.

SELECT org_id
FROM cult_xref INNER JOIN cat_xref USING (org_id)
WHERE (cult_id,cat_id) = (2,6)

For a nice introduction to joins, see A Visual Explanation of SQL Joins