sql case when

SQL Server Case Statement:
CASE [expression]  
   WHEN [value | Boolean expression] THEN [return value] 
   ELSE [return value]
END

Example 1:
declare @Gender nvarchar(6)
set @Gender='M' select case when @Gender='M' then 'Male' else 'Female' End 'Gender'

#Results:  
Gender
Male

 Example 2:  
declare @Gender nvarchar(6)
set @Gender='F' select case when @Gender='M' then 'Male' else 'Female' End 'Gender'

#Results:
Gender
Female

Example 3:
select Num, case Num  
                 when 100 then 'A'  
                 when 90 then 'B'  
                 when 80 then 'C'  
                 when 70 then 'D'
                 when 60 then 'E'  
             end 'Grade' from (
     select (100)Num union
     select (90) union
     select (80) union  
     select (70) union
     select (60)
)v1

#Results:
Num Grade
60 E
70 D
80 C
90 B
100 A