Combine greatest, sum, and case when

Question

All,
I have the following view
Select table1.field1,
greatest(sum(table1.field3) - case when table1.oneorzerocolumn=1 then table1.field2 else table1.field4 end,0) as NetAbove0
from table1
group by table1.field1;
I seem to be having trouble figuring out the best way to accomplish this, though, as whenever I try to execute this query I get not a valid group by expression. How can I combine the greatest function and the aggregate sum function without creating a separate view?
Thanks in advance.
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
PL/SQL Release 11.2.0.2.0 - Production
CORE     11.2.0.2.0     Production
TNS for Linux: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - Production
Edited by: 929933 on Mar 14, 2013 1:32 PM

Answer 1

929933 wrote:
@ sb92075 would you care to elaborate on exactly what was missing?If you would care to read the link sb92075 posted you will understand by yourself:
What is particularly important in that FAQ is:
6) Tables/Indexes
7) Sample Data
8) Expected Output
9) Formatting with {noformat}{noformat} Tags
You have posted an unformatted code and did not provide proper input.
Coming to your problem the issue is quite clear. If you use a GROUP BY clause then all field which are not returned as aggregated function shall be included in the GROUP BY clause.
And this has a logic.
Your initial query (formatted in a decent way):SELECT table1.field1
, GREATEST (SUM (table1.field3)
- CASE
WHEN table1.oneorzerocolumn = 1 THEN
table1.field2
ELSE table1.field4
END, 0) AS netabove0
FROM table1
GROUP BY table1.field1;
is not correct.
The column used in the query table1.oneorzerocolumn, table1.field2 and table1.field4 are not part of the GROUP BY and not used in aggregation functions.
So how could you determine the value, i.e. table1.oneorzerocolumn, if for the same value of table1.field1 you have different values of table1.oneorzerocolumn?
You are aggregating by field1 so which value do you want to use for non aggregated columns?
Everything will be easier to understand if you can post some sample data, explain the logic you want to apply and post the expected output for the sample data you have posted.
Regards.
Al