Group by and decode function

Question

Can I use a group by on a decode?
I am using the sql below and get an error message when I
try to use the group by on a decode.
select decode(assignment.catcodeid,
'D', 'SERVICE REQUESTS AND MAINTENANCE',
'U', 'SERVICE REQUESTS AND MAINTENANCE',
'P', 'SERVICE REQUESTS AND MAINTENANCE',
'E', 'SERVICE REQUESTS AND MAINTENANCE',
'R', 'SERVICE REQUESTS AND MAINTENANCE',
'T', 'EDUCATION',
'O', 'OVERHEAD',
'L', 'UNPAID LEAVE',
'V', 'VACATION',
'S', 'SICK PAY',
'H', 'HOLIDAY',
'C', 'COMP TIME',
'UNKNOWN ACTIVITY') "ACTIVITY",
assignment.catcodeid, assignment.esthrs,
SUM(ASSIGNMENT.ESTHRS)
FROM ASSIGNMENT
GROUP BY ACTIVITY, catcodeid, esthrs
The error is
ORA-00904: "ACTIVITY": invalid identifier
It is understood that Activity is not a field
on the table.
But, is there a way that I can group by the result of
a decode function or what other method/advice I can use to
group by the result of this.
Thanks is advance.

Answer 1

Hello
You just need to put the decode statement in the group by as well, you can't just use the alias...And if you just group by the catcodeid, you won't be putting all of the SERVICE REQUESTS AND MAINTENANCE rows together. But, because you are selecting the catcodeid aswell as decoding it, that will happen anyway.
HTH