In a simple case statement, one value or variable is checked against multiple possible answers. The code below is an example of a simple case statement:
SELECT CASE DATEPART(WEEKDAY, GETDATE())
WHEN 1 THEN 'Sunday'
WHEN 2 THEN 'Monday'
WHEN 3 THEN 'Tuesday'
WHEN 4 THEN 'Wednesday'
WHEN 5 THEN 'Thursday'
WHEN 6 THEN 'Friday'
WHEN 7 THEN 'Saturday'
END