Get result satisfy both condition in Decode function

Question

I have code working as long as set of codes total is not the same (code1(21)+code2(22)=43, code1(18)+code2(25)=43)
I got wrong data based on following
select dt,
avg(decode(code1+code2,'21'+'22',midpoint)) C1,
avg(decode(code1+code2,'18'+'25',midpoint)) C2
from tablename
where dt>=to_date('02/27/2000','mm/dd/yyyy')
and dt<=to_date('2/26/2001','mm/dd/yyyy')
and ( (code1=21 and code2=22)
or (code1=18 and code2=25)
) group by dt
How come I can use decode function based on code1 and code2.
Linda

Answer 1

Evening Linda,
I have tried yourt sql with the following sample data from table T1 ...
select C1,D1,N1,N2,N3 from T1;
C1     D1     N1     N2     N3
A     02/27/2000     18     25     -1
B     02/27/2000     21     22     -1
Note : N3 is your midpoint column from your sql.
Test SQL below
select C1,D1,N1,N2,
avg(decode(N1+N2,'21'+'22',N3,N1+N2)) AVG_A,
avg(decode(N1+N2,'18'+'25',N3,N1+N2)) AVG_B
from T1
where D1 BETWEEN to_date('02/27/2000','mm/dd/yyyy') AND to_date('2/26/2001','mm/dd/yyyy')
and
((N1=21 and N2=22) or (N1=18 and N2=25))
group by C1,D1,N1,N2
Based on that data, I always get N3 (midpoint) back as N1+N2 = 43 as shown below ...
C1     D1     N1     N2     AVG_A     AVG_B
A     02/27/2000     18     25     -1     -1
B     02/27/2000     21     22     -1     -1
When I change the decode(N1+N2.. to say decode(N1+N2+1.. then I get the second part of the decode back (I shorted the SQL since I only have 2 test records anyway) ...
select C1,D1,N1,N2,
avg(decode(N1+N2 +1 ,'21'+'22',N3,N1+N2)) AVG_A,
avg(decode(N1+N2 +1 ,'18'+'25',N3,N1+N2)) AVG_B
from T1
group by C1,D1,N1,N2
C1     D1     N1     N2     AVG_A     AVG_B
A     02/27/2000     18     25     43     43
B     02/27/2000     21     22     43     43
When the N1+N2 do not match to 43, the FOURTH part of the decode is called, which you did not specify in your original sql (there is only 3, nothing came after midpoint). Maybe I am not understanding what you want for an answer based on this sample data that I have tried. Maybe show a data set that you have showing what you are wanting for an answer. Remember DECODE has 4 parts to it, if they dont match the search ('21'+'22') then the FOURTH part is returned, which you did not define, so a NULL would get returned (see below).
select C1,D1,N1,N2,
avg(decode(N1+N2 +1 ,'21'+'22',N3)) AVG_A,
avg(decode(N1+N2 +1 ,'18'+'25',N3)) AVG_B
from T1
group by C1,D1,N1,N2
C1     D1     N1     N2     AVG_A     AVG_B
A     02/27/2000     18     25          
B     02/27/2000     21     22          
Thanks,
Tyler D. ([email protected])