How do I do multiple CASE WHEN conditions using SQL Server 2008?

In SQL Server 2008, the CASE WHEN statement is very useful when you want to apply conditional logic directly within your SQL queries. It works like an IF-ELSE statement in programming, allowing you to return different values depending on certain conditions. You can use multiple CASE WHEN conditions to handle more complex logic.

Here are a few ways to do it:

Simple CASE – Compares a single column to multiple values. Example:

 SELECT 
    EmployeeID,
    CASE DepartmentID
        WHEN 1 THEN 'HR'
        WHEN 2 THEN 'Finance'
        WHEN 3 THEN 'IT'
        ELSE 'Other'
    END AS DepartmentName
FROM Employees;

 This checks one column (DepartmentID) against multiple possible values.

Searched CASE – Allows more flexibility by evaluating logical conditions instead of equality:

 SELECT 
    EmployeeID,
    Salary,
    CASE 
        WHEN Salary < 3000> 7000 THEN 'High'
        ELSE 'Unknown'
    END AS SalaryRange
FROM Employees;

•  This type is often used when you need ranges or more complex comparisons.
  
• Multiple CASE conditions in one query – You can use more than one CASE statement within the same SELECT to handle different fields.
  

 In short, using multiple CASE WHEN conditions in SQL Server 2008 makes your queries powerful and flexible. It allows you to categorize, transform, or customize your result sets without writing separate queries.