Question

I have two MySQL tables, j and t, with a third normalising table, jt.

t.tID

j.jID

jt.status
jt.tID
jt.jID

How can I select all j where all jt.status=”x”? That is, I want to select when all jt of a j are x, not just when one or more jt of a j are x.

I think table t may be irrelevant in this.

(I hope I make myself understood, I’m finding it rather hard to explain. Comment questions if you want.)

Answer 1

It appears as though you want the not exists clause.

select jt.*
  from jt
 where not exists ( select 1 from jt where status <> 'x' and jID = jt.jID )

This selects everything from jt where not a single value that isn’t x exists in that table.