How to Use CASE Function in SQL
In this article I am going to explain how to use case function in SQL.
Introduction
In SQL Server there are two type of function which are used to manipulate data in database.
- System define function
- User define function
SQL server provide a list of system define function which are used to manipulate data. These system define function are predefine. We can't change functionality of these system define function. There are many situation where we need a function which performer some specific task according to our need. There function are known as user define function.
Case Function
Case function execute a sequence of statement depending upon condition. CASE function in SQL operates by comparing the first expression to the expression in each WHEN clause for equivalency. Expressions which are equivalent in Case function, expression in the THEN clause will be executed.
Example
|
declare
@st_marks int,
@st_result varchar(15)
select @st_marks = 80
select @st_result =
case
when @st_marks>70 then 'A Grade'
when @st_marks<70 and @st_marks>=50 then 'B Grade'
when @st_marks < 50 then 'Fail'
end
print 'result = ' + @st_result
|
Output
