sql - Average of multiple columns

Question

I have a table called Request and the data looks like:

Req_ID    R1   R2   R3   R4   R5

R12673    2    5    3    7    10
R34721    3    5    2    1    8
R27835    1    3    8    5    6

Now I want to display the average of R1,R2,R3,R4 and R5

So I wrote a query like:

Select Req_ID, Avg(R1+R2+R3+R4+R5) as Average
from Request
Group by Req_ID

But I just get the sum of R1,R2,R3,R4 and R5 not the average? Where am I doing wrong.

Answer 1

You don't mention if the columns are nullable. If they are and you want the same semantics that the AVG aggregate provides you can do (2008)

SELECT *,
       (SELECT AVG(c)
        FROM   (VALUES(R1),
                      (R2),
                      (R3),
                      (R4),
                      (R5)) T (c)) AS [Average]
FROM   Request  

The 2005 version is a bit more tedious

SELECT *,
       (SELECT AVG(c)
        FROM   (SELECT R1
                UNION ALL
                SELECT R2
                UNION ALL
                SELECT R3
                UNION ALL
                SELECT R4
                UNION ALL
                SELECT R5) T (c)) AS [Average]
FROM   Request