Get difference between 2 lists of values in T-SQL

get-difference-between-2-lists-of-values-in-tsql.sql

-- Using common table expressions
with
-- Supply list A
a (i) as (select i from (values 
  ('6GA00215S'),
  ('6GU00208S'),
  ('6PO00396I'),
  ('6PO00398I')
) A(i)),
-- Supply list B
b (i) as (select i from (values 
  ('6GA00215S'),
  ('6GU00208S')
) B(i))
-- Find all elements in list A that don't exist in list B
select a.i from a left join b on a.i = b.i where b.i is null