AVG() aggregate with CASE

i have 2 columns of type decimal that are divided and rounded and
return zero if the divisor is zero. it all works fine until i try to
AVG() them. now it seems my CASE to avoid dividing by zero is no
longer working...or i'm just approaching it all the wrong way. my
brain is a bit fried from staying up late to meet a deadline and i was
wondering if someone could give some advice.
SELECT CASE a.Value2 WHEN 0 THEN 0 ELSE ROUND((b.Value1 / b.Value2 *
1000) * 100, 2, 1) END AS Rating FROM a INNER JOIN b ON a.ID = b.ID
b.Value1 = 101664
a.Value2 = 7730
Rating = 1.31
i now try putting the AVG() function to work like this:
SELECT CASE a.Value2 WHEN 0 THEN 0 ELSE AVG( ROUND((b.Value1 / b.Value2
* 1000) * 100, 2, 1) ) END AS Rating FROM a INNER JOIN b ON a.ID =
b.ID GROUP BY a.Value2
if i have 5 rows of results .96, .97, .98, 1.13, 1.31, then it works i
get one record with the Rating = 1.07. yay!
the problem comes in where sometimes, the Values are 0. before using
the AVG() function, the CASE took care of these columns so that my
Rating results would be 0. but now i keep getting a "Divide by zero
error encountered". if the CASE is working, it shouldn't even try the
AVG() calculation right? or am i approaching this the wrong way? and
no, i can't use the SET ANSI_WARNINGS OFF because we're not using
stored procedures in this case.
thanks for any input or insight you may provide!
susieWhy not avoid the 0 problem by putting in a WHERE clause? ie
WHERE value1 > 0
AND value2 > 0
If that's not going to work, post some more sample values for tables a and b
.
Thanks
Damien
"TuBuGuRL" wrote:

> i have 2 columns of type decimal that are divided and rounded and
> return zero if the divisor is zero. it all works fine until i try to
> AVG() them. now it seems my CASE to avoid dividing by zero is no
> longer working...or i'm just approaching it all the wrong way. my
> brain is a bit fried from staying up late to meet a deadline and i was
> wondering if someone could give some advice.
> SELECT CASE a.Value2 WHEN 0 THEN 0 ELSE ROUND((b.Value1 / b.Value2 *
> 1000) * 100, 2, 1) END AS Rating FROM a INNER JOIN b ON a.ID = b.ID
> b.Value1 = 101664
> a.Value2 = 7730
> Rating = 1.31
> i now try putting the AVG() function to work like this:
> SELECT CASE a.Value2 WHEN 0 THEN 0 ELSE AVG( ROUND((b.Value1 / b.Value2
> * 1000) * 100, 2, 1) ) END AS Rating FROM a INNER JOIN b ON a.ID =
> b.ID GROUP BY a.Value2
> if i have 5 rows of results .96, .97, .98, 1.13, 1.31, then it works i
> get one record with the Rating = 1.07. yay!
> the problem comes in where sometimes, the Values are 0. before using
> the AVG() function, the CASE took care of these columns so that my
> Rating results would be 0. but now i keep getting a "Divide by zero
> error encountered". if the CASE is working, it shouldn't even try the
> AVG() calculation right? or am i approaching this the wrong way? and
> no, i can't use the SET ANSI_WARNINGS OFF because we're not using
> stored procedures in this case.
> thanks for any input or insight you may provide!
> susie
>|||hi damien,
thanks for the reply. the WHERE clause is a good idea, but i don't
want to exclude these values, i need them to show up as averaged 0 in
my report.
i just realized that in my post above it's supposed to say "... ROUND(
(b.Value1 / a.Value2) ) ..." NOT "... ROUND( (b.Value1 / b.Value2) )
..."
anyway more sample data:
a.Value2 = 5910
b.Value1 = 120779
Rating = 2.04
5 different Ratings: 2.04, 1.01, 0.98, 0.91, 0.41
Avg() rating = 1.07
data used when i receive the error:
a.Value2 = 0
b.Value2 = 0
Rating = .0000000000000000
5 different Ratings: all .0000000000000000
shouldn't the CASE i use in the SELECT avoid even trying to AVG() the 0
Ratings?
thanks,
susie|||Put the CASE inside the AVG
...
AVG(CASE a.Value2 WHEN 0 THEN 0 ELSE ROUND(...) END)
...
TuBuGuRL wrote:
> i have 2 columns of type decimal that are divided and rounded and
> return zero if the divisor is zero. it all works fine until i try to
> AVG() them. now it seems my CASE to avoid dividing by zero is no
> longer working...or i'm just approaching it all the wrong way. my
> brain is a bit fried from staying up late to meet a deadline and i was
> wondering if someone could give some advice.
> SELECT CASE a.Value2 WHEN 0 THEN 0 ELSE ROUND((b.Value1 / b.Value2 *
> 1000) * 100, 2, 1) END AS Rating FROM a INNER JOIN b ON a.ID = b.ID
> b.Value1 = 101664
> a.Value2 = 7730
> Rating = 1.31
> i now try putting the AVG() function to work like this:
> SELECT CASE a.Value2 WHEN 0 THEN 0 ELSE AVG( ROUND((b.Value1 / b.Value2
> * 1000) * 100, 2, 1) ) END AS Rating FROM a INNER JOIN b ON a.ID =
> b.ID GROUP BY a.Value2
> if i have 5 rows of results .96, .97, .98, 1.13, 1.31, then it works i
> get one record with the Rating = 1.07. yay!
> the problem comes in where sometimes, the Values are 0. before using
> the AVG() function, the CASE took care of these columns so that my
> Rating results would be 0. but now i keep getting a "Divide by zero
> error encountered". if the CASE is working, it shouldn't even try the
> AVG() calculation right? or am i approaching this the wrong way? and
> no, i can't use the SET ANSI_WARNINGS OFF because we're not using
> stored procedures in this case.
> thanks for any input or insight you may provide!
> susie
>