The case expression implementation is based on conditional logic to return a value _mssql

In our development process, we often need to return a value for a column, based on conditional logic, then we need to use the case expression.

For example, the following query to the Products table uses a CASE expression in the SELECT statement to generate information that describes the value of the CategoryID column.

The SQL code is as follows:

--Setting the database context use
TSQLFundamentals2008;
Go

SELECT Productid,productname,categoryid, Case
CategoryID when
1 THEN ' beverages ' when
2 THEN ' Condiments ' when
3 THEN ' Dairy products ' when
4 THEN ' confections ' when
5 THEN ' grains/cereals ' when
6 TH EN ' Meat/poultry ' when
7 THEN ' produce ' if
8 THEN ' seafood '
ELSE ' unkown Category ' end as
Categoryn Ame from
production.products;

Query results: