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Help with using a case statement within a union

Posted on 2011-09-08
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Last Modified: 2012-05-12
I am trying to modify a query so that I get different output depending on a specific value in one of the fields.  The query is something I found elsewhere and modified it to output a list of classes by course groups - like:

Group 100
 class 101
 class 102

Group 200
 class 201
 class 202

etc.

Now I need to have a different display only when the group level is 600 it will show something like:

Group 100
 class 101
 class 102

Group 200
 class 201
 class 202

Group 600
 no classes

I know I need a case but can't figure out how to incorporate that into my existing query - though I've been trying.  In the real query, I"m building some HTML but I've eliminated that here for the sake of clarity.  Anything that gives me alternate output for the 600 level will give me enough to work with.  The original query is attached.

Many thanks in advance.

SELECT Description
FROM
(
SELECT g.groupNum, 0 AS classId, g.groupName AS Description
FROM tbl_AdultEd_ClassGroups g where g.groupDisplay=1
UNION ALL
SELECT c.groupNum, c.classID, c.className AS Description 
FROM tbl_AdultEd_Classes c 
where c.classDisplay=1 
) sub
ORDER BY groupNum, classId

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Question by:saabStory
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2 Comments
 
LVL 5

Accepted Solution

by:
zvytas earned 500 total points
ID: 36503386
Try the folliwing:

SELECT CASE WHEN classId <> 0 AND groupNum = 600 THEN 'no classes' ELSE Description  END AS Description
FROM
(
SELECT g.groupNum, 0 AS classId, g.groupName AS Description
FROM tbl_AdultEd_ClassGroups g where g.groupDisplay=1
UNION ALL
SELECT c.groupNum, c.classID, c.className AS Description
FROM tbl_AdultEd_Classes c
where c.classDisplay=1
) sub
ORDER BY groupNum, classId

I assumed level is stored in groupNum.
0
 

Author Closing Comment

by:saabStory
ID: 36504779
Perfect!  Thanks so much!!!
0

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