t-sql 2008 nested case statements

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t-sql 2008 nested case statements

wendy elizabeth

SSCoach

Points: 16915
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February 23, 2014 at 9:43 pm

#396309

I have a question about understanding nested case statements in sql server 2008:
The sql looks like the folloiwng:
select numberofcases
from inventory
where inventory_cnt > 1000
(when select top 1
from inventory
where inventory_cnt > 750
then numberofcases = 750 * 30
when select top 2
from inventory
where inventory_cnt > 975
then numberofcases = 975 * 35
when select top 3
from inventory
where inventory_cnt > 1025
then numberofcases = 1025 / 10
when select top 4
from inventory
where inventory_cnt > 1050
then numberofcases = 1050 / 5) c * 2
as casesused, select CustomerNumber from inventory
I would like you to explain the following:
1. There are 4 when statements. Will the logic hit each when statemnet or will the logic
stop once the first when statement is true?
2. Would you explain what the c* 2 means from the school listed above?

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ChrisM@Work SSC Guru Points: 186127 More actions · Answer 1

wendy elizabeth (2/23/2014)
I have a question about understanding nested case statements in sql server 2008:
The sql looks like the folloiwng:
select numberofcases
from inventory
where inventory_cnt > 1000
(when select top 1
from inventory
where inventory_cnt > 750
then numberofcases = 750 * 30
when select top 2
from inventory
where inventory_cnt > 975
then numberofcases = 975 * 35
when select top 3
from inventory
where inventory_cnt > 1025
then numberofcases = 1025 / 10
when select top 4
from inventory
where inventory_cnt > 1050
then numberofcases = 1050 / 5) c * 2
as casesused, select CustomerNumber from inventory
I would like you to explain the following:
1. There are 4 when statements. Will the logic hit each when statemnet or will the logic
stop once the first when statement is true?
2. Would you explain what the c* 2 means from the school listed above?

Homework is easy with Google. Type in TSQL CASE and choose the first result returned. It will be this: http://technet.microsoft.com/en-us/library/ms181765.aspx which answers your first question. Your second question? Multiply c (whatever that is) by two.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden