Question

I have a table which contains student grades (SAG). I need to show all grades that aren’t NULL or '' from one row based on ID and ResultGroup and have all other grades coming from another row based on ID and ResultGroup in the same table.

TABLE - SAG

ID     RESULTGROUP     GRADE
-----------------------------
102    AC              C
102    ACPJ            B
124    AC              A
124    ACPJ            
242    AC              B
242    ACPJ            
101    AC              D
101    ACPJ            C

What I’m trying to work out is how to get the results from ResultGroup ACPJ and only those from ResultGroup AC if there is a NULL or '' in the Grade for that ID.

END RESULT? Something like…

SAG_COMBINED

ID     FinalGrade
-----------------
102    B
124    A
242    B
101    C

Answer 1

SELECT acpj.ID
   , CASE
        WHEN acpj.Grade IS NULL OR acpj.Grade = '' THEN ac.Grade
        ELSE acpj.Grade
     END AS FinalGrade
FROM SAG AS acpj
INNER JOIN SAG AS ac ON acpj.ID = ac.ID
WHERE acpj.ResultGroup = 'ACPJ'
   AND ac.ResultGroup = 'AC'