Introduction to Case Statement in SQL

               Introduction to Case Statement in SQL

Many times there is a requirement like you have to display data based on some condition 

Let me explain by a example

Suppose in your table you have a column Gender and you have inserted value like

M which denotes Male

F which denotes Female

If no values then Unknown

So for this type of scenarios we use case Statement 

Below is the Example of Case Statement

create table employee

(name nvarchar(30),Gender nvarchar(15))

insert into employee values('xyz','M'),('abc','F'),('pqr',Null)

select * from employee 

select name,case gender

when 'M' then 'Male'

when 'F' then 'Female'

else 'Unknown'

end

from employee 

Don't forget to put end after finishing case statement otherwise it will throw an error.

The Case statement will check data for Gender column it will check if M then display Male

if F then Female else display Unknown

Note: you can achieve this result also by using if else if but when no. of condition are more it's a good practice to use Case Statement.