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

Something like this, using FULL JOIN:

SELECT
  CASE 
    WHEN EXISTS (
      SELECT * FROM s1 FULL JOIN s2 ON s1.Item = s2.Item
      WHERE s1.Item IS NULL OR s2.Item IS NULL
      )
    THEN 'Elements in tableA and tableB are not equal'
    ELSE 'Elements in tableA and tableB are equal'
  END

This has the virtue of short-circuiting on the first non-match, unlike other solutions that require 2 full scans of each table (once for the COUNT(*), once for the JOIN/INTERSECT).

Estimated cost is significantly less than other solutions.