sub grouping on flags in SQL

Question

I want to subgroup my PK1 and PK2 fields based on the four flags I have. If I have any of flags as blank then the results should be Yes for that PK1. If all the four flags in all PK2 for that particular PK1 is X then it should return no.

PK1 PK2 Flag1   Flag2   Flag3   Flag4  
100 10  X       
100 20          X   
100 30              
200 40  X   X   X   X  
200 50  X   X   X   X  
300 A10             X  
300 A20     X       

The expected Output is :

100 Yes  
200 No  ( as all flag values for each PK2 is X)  
300 Yes  

Any pointers how should I solve this in SQL Regards,

Answer 1

You can try the below -

select pk1, case when max(flag1) is not null and max(flag2) is not null and max(flag3) is not null and max(flag4) is not null then 'No' else 'Yes' end as flagval
from tablename
group by pk1

Answer 2

SELECT pk1, CASE SUM(flag1='' + flag2='' + flag3='' + flag4='')
            WHEN 0 
            THEN 'No'
            ELSE 'Yes'
            END
FROM table
GROUP BY pk1

The query assumes that none flag value is NULL.