TSQL Comparing two Sets

Question

When two sets are given

s1 ={ a,b,c,d} s2={b,c,d,a}

(i.e)

TableA

Item
a
b
c
d

TableB

Item
b
c
d
a

How to write Sql quer

Answer 1

Since this thread was very helpful to me, I thought I'd share my solution.

I had a similar problem, perhaps more generally applicable than this specific single-set comparison. I was trying to find the id of an element that had a set of multi-element child elements that matched a query set of multi-element items.

The relevant schema information is:

table events, pk id
table solutions, pk id, fk event_id -> events
table solution_sources, fk solutionid -> solutions
   columns unitsourceid, alpha

Query: find the solution for event with id 110 that has the set of solution_sources that match the set of (unitsourceid, alpha) in ss_tmp. (This can also be done without the tmp table, I believe.)

Solution:

with solutionids as (
  select y.solutionid from (
     select ss.solutionid, count(ss.solutionid) x 
        from solutions s, solution_sources ss 
        where s.event_id = 110 and ss.solutionid = s.id 
        group by ss.solutionid
  ) y where y.x = ( select count(*) from ss_tmp )
) 
select solutionids.solutionid  from solutionids where
(
select case
   when count(*) = ( select count(*) from ss_tmp ) then true
   else false
   end
    from 
       ( SELECT unitsourceid, alpha FROM solution_sources 
            where solutionid = solutionids.solutionid
          INTERSECT
         SELECT unitsourceid, alpha FROM ss_tmp ) x
)

Tested against a test query of 4 items and a test db that had a matching solution (same number of child elements, each that matched), several completely non-matching solutions, and 1 solution that had 3 matching child elements, 1 solution that had all 4 matching child elements, plus an additional child, and 1 solution that had 4 child elements of which 3 of the 4 matched the query. Only the id of the true match was returned.

thanks a lot -Linus