SQL Server - Case Statement

Question

I'm almost certain you cannot do this within the context of the case statement, and I haven't been able to find any documentation about it, but is it possible to do the following:

SELECT CASE WHEN testValue > 2 
THEN testValue(Without Repeating it) ELSE FailValue)
END 
FROM Table 

A better more thorough example:

Select CASE WHEN (Foo-stuff+bar) > 2 
THEN Conditional statement without >2 Else "Fail"
END 
FROM TABLE

I am looking for a way to create a select without repeating the conditional query.

EDIT: Due to a poor example on my part, and the lack of answers I was looking for:

testValue = (Table.A / Table.B) * Table.C Table.D

SELECT CASE WHEN testValue > 2 
THEN testValue ELSE FailValue)
END 
FROM Table 

Answer 1

Like so

DECLARE @t INT=1

SELECT CASE
            WHEN @t>0 THEN
                CASE
                    WHEN @t=1 THEN 'one'
                    ELSE 'not one'
                END
            ELSE 'less than one'
        END

EDIT: After looking more at the question, I think the best option is to create a function that calculates the value. That way, if you end up having multiple places where the calculation needs done, you only have one point to maintain the logic.

Answer 2

The query can be written slightly simpler, like this:

DECLARE @T INT = 2 

SELECT CASE 
         WHEN @T < 1 THEN 'less than one' 
         WHEN @T = 1 THEN 'one' 
         ELSE 'greater than one' 
       END T

Answer 3

I am looking for a way to create a select without repeating the conditional query.

I'm assuming that you don't want to repeat Foo-stuff+bar . You could put your calculation into a derived table:

SELECT CASE WHEN a.TestValue > 2 THEN a.TestValue ELSE 'Fail' END 
FROM (SELECT (Foo-stuff+bar) AS TestValue FROM MyTable) AS a

A common table expression would work just as well:

WITH a AS (SELECT (Foo-stuff+bar) AS TestValue FROM MyTable)
SELECT CASE WHEN a.TestValue > 2 THEN a.TestValue ELSE 'Fail' END    
FROM a

Also, each part of your switch should return the same datatype, so you may have to cast one or more cases.

Answer 4

We can use case statement Like this

select Name,EmailId,gender=case 
when gender='M' then 'F'
when gender='F' then 'M'
end
 from [dbo].[Employees]

WE can also it as follow.

select Name,EmailId,case gender
when 'M' then 'F'
when 'F' then 'M'
end
 from [dbo].[Employees]