仅当所有连接的条具有相同的列值时才返回foo

Question

I have 2 tables foo and bar , there is a one to many relation between the two. I want to get a list of foos where all the corresponding bars have a column status = 'CLOSED' . How should I write that query?

SELECT f.* 
FROM foo f
JOIN bar b ON b.foo_bk = f.bk
WHERE b.status = 'CLOSED'

The current query will return the foo even if it has one bar with a different status value. I have been looking at CASE and IF queries but I don't know how to get them to work for this case.

Answer 1

Try to add subquery as below

SELECT f.* 
FROM foo f
JOIN bar b ON b.foo_bk = f.f_bk
WHERE b.status = 'CLOSED'
AND not exists (select 1
                from bar b2
                where b2.foo_bk = f.f_bk
                and b.status <> 'CLOSED')

Answer 2

SELECT f.* FROM foo f
JOIN bar b ON b.foo_bk = f.f_bk
WHERE f.f_bk IN (SELECT b.bk FROM bar b WHERE b.status = 'CLOSED')
AND f.f_bk NOT IN (SELECT b.bk FROM bar b WHERE b.status <> 'CLOSED')

This query will give you all the rows that exist in bar with status 'CLOSED', while omitting rows with other statuses.