(probably) very simple SQL query needed - sql

Question

Having a slow day....could use some assistance writing a simple ANSI SQL query.
I have a list of individuals within families (first and last names), and a second table which lists a subset of those individuals. I would like to create a third table which flags every individual within a family if ANY of the individuals are not listed in the second table. The goal is essentially to flag "incomplete" families.
Below is an example of the two input tables, and the desired third table.
As I said...very simple...having a slow day. Thanks!

Answer 1

I think you want a left join and case expression:
select t1.*,
(case when t2.first_name is null then 'INCOMPLETE' else 'OK' end) as flag
from table1 t1 left join
table2 t2
on t1.first_name = t2.first_name and t1.last_name = t2.last_name;
Of course, this marks "Diane Thomson" as "OK", but I think that is an error in the question.
EDIT:
Oh, I see. The last name defines the family (that seems like a pretty big assumption). But you can do this with window functions:
select t1.*,
(case when count(t2.first_name) over (partition by t1.last_name) =
count(*) over (partition by t1.last_name)
then 'OK'
else 'INCOMPLETE'
end) as flag
from table1 t1 left join
table2 t2
on t1.first_name = t2.first_name and t1.last_name = t2.last_name;

Answer 2

That's not simple, at least not in SAS :-)
Standard SQL, when Windowed Aggregates are supported:
select ft.*,
-- counts differ when st.first_name is null due to the outer join
case when count(*) over (partition by ft.last_name)
= count(st.first_name) over (partition by ft.last_name)
then 'OK'
else 'INCOMPLETE'
end
from first_table as ft
left join second_table as st
on ft.first_name = st.first_name
and ft.last_name = ft.last_name
Otherwise you need to a standard aggregate and join back:
select ft.*, st.flag
from first_table as ft
join
(
select ft.last_name,
case when count(*)
= count(st.first_name)
then 'OK'
else 'INCOMPLETE'
end as flag
from first_table as ft
left join second_table as st
on ft.first_name = st.first_name
and ft.last_name = st.last_name
group by ft.last_name
) as st
on ft.last_name = st.last_name

Answer 3

It is pretty easy to do in SAS if you want to take advantage of its non-ANSI SQL feature of automatically re-merging aggregate function results back onto detail records.
select
a.first
, a.last
, case when 1=max(missing(b.last)) then 'INCOMPLETE'
else 'OK'
end as flag
from table1 a left join table2 b
on a.last=b.last and a.first=b.first
group by 2
order by 2,1
;