This is not what he wants.
He wants all keys that have only true for x.
> Why areyou using the sub select. If you just want all the key1 where x is
> true then the following will work
>
> SELECT DISTINCT(key1) FROM a WHERE x = TRUE;
>
> If you want all rows and don't care about duplicates then remove the
> distinct.
>
> Hope this helps
>
> >
> > I've seen many posts saying that using IN is not optimal and replacing
> > it with EXISTS is much better. I've read the only docs but I can't
> > understand the difference between the two or how to convert.
> >
> > Can someone point me to some other docs or explain to me how to convert?
> > Or is my table schema wrong?
> >
> > Thanks!
> >
> > Jc
> >