Some times we need to apply switch case in sql query when we retrieved the data. At that time this blog may help you.

let's assume a table is given as follow:

username password roleid
aaa sss 1
bbb fff 1
ccc gdfg 2
ddd fsdfsd 2

we want the data is such manner

1=admin
2=client

username password roleid
aaa sss admin
bbb fff admin
ccc gdfg client
ddd fsdfsd client

Then we can write query like this:

select CASE RoleID WHEN 1 THEN 'Admin' ELSE 'Client' END as RoleID from tbl_User