CASE.. WHEN statement.. Query not working

Question

Hi,
Can someone help me to correct the following code:
select * from(
select col1,col2,
CASE
WHEN
Percentage >=75 THEN 'red'
ELSE
'green'
end as color from (select
ROUND(((COUNT(CASE WHEN class ='A' THEN 1 END)/
nullif((SUM(CASE WHEN class ='B' THEN 1 END)+ SUM(CASE WHEN class ='C' THEN 1 END)),0))*100),1)) as Percentage, col4,col5
from table
group by class,col2
order by class;P.S: Percentage is the alias for the complex query, I am using.... it is not the column name.
Front end is APEX, once the code is syntactically correct, I can use it in APEX. So didn't post it in APEX forum.

Answer 1

Hi,
Emy_Jack wrote:
I am sorry..
OK the structure of the table is the following
TABLE NAME: STATISTICS
STRUCTURE:
REGION VARCHAR2(50),
COUNTRY VARCHAR2(50),
SITE VARCHAR2(50),
GROUP VARCHAR2(50),
GROUP isn't the best name for a column; it will get mixed up with the keyword GROUP used in GROUP BY.
Why not name your column something that is not an Oracle keyword, such as grp or stats_group?
LANGUAGE VARCHAR2(50),
PEOPLE VARCHAR2(50)Posting the table structure is better than nothing, but it would be even better to post a working CREATE TABLE statement, so the people who want to help you can re-create the problem for themselves, and test their ideas.
So the query is:
SELECT * FROM(
SELECT REGION,COUNTRY,SITE,
ROUND(((COUNT(CASE WHEN GROUP_FIRST ='A' THEN 1 END)/
There's no column called group_<b>first</b> in the table structure you posted.
NULLIF((SUM(CASE WHEN GROUP ='B' THEN 1 END)+
SUM(CASE WHEN GROUP ='A' THEN 1 END)),0))*100),1)
AS "PERCENTAGE",
CASE
WHEN
"PERCENTAGE" >=75 THEN 'red'You can't define a column alias (such as percentage) and reference it in the same SELECT clause. In fact, the ORDER BY clause is the only place where you can use a column alias in the same sub-query where it was defined.
If you define a column alais in a sub-query, then you can use it anywhere you want to in a super-query. In this query, do the GROUP BY and compute percentage in a sub-query, then compute color (referencing percentage) in the main query.
ELSE
'green'
end "Color", group,peopleIf group and people are not in the GROUP BY clause, then you can't use them by themselves in the SELECT clause like this.
FROM
STATISTICS
WHERE GROUP IN ('B','A')
GROUP BY REGION,COUNTRY,SITE
ORDER BY REGION,COUNTRY);ORDER BY in a sub-query is usually just a waste of resources. The order will not necessarily be preserved in the main result set. Don't use ORDER BY in the sub-query here, use it only in the main query.
ERROR:
ORA-00904: "PERCENTAGE": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:   
*Action:
Error at Line: 8 Column: 5Edited by: Emy_Jack on Mar 16, 2013 3:06 AMAs an example of how to use a sub-query to define an alias:
WITH     got_percentage     AS
     SELECT       region, country, site
     ,       AVG ( CASE
                         WHEN  group_first = 'A' THEN  100
                                              ELSE    0
                     END
                )          AS percentage
     FROM      statistics
     WHERE       group_first     IN ('A', 'B')
     GROUP BY  region, country, site
SELECT       region, country, site
,       percentage          -- if wanted
,       CASE
           WHEN  percentage >= 75  THEN  'red'
                                           ELSE  'green'
       END          AS color
FROM      got_percentage
ORDER BY  region_country
;If you'd care to post CREATE TABLE and INSERT statements for a little sample data, and the results you want from that sample data, then I could test this.
Edited by: Frank Kulash on Mar 16, 2013 7:17 AM
Added query.