10. SQLServer : 表达式 {alert type="info"}-- 语法 --Simple CASE expression: CASE input_expression WHEN when_expression THEN result_expression [ ...n ] [ ELSE else_result_expression ] END --Searched CASE expression: CASE WHEN Boolean_expression THEN result_expression [ ...n ] [ ELSE else_result_expression ] END -- 示例一 SELECT ProductNumber, Category = CASE ProductLine WHEN 'R' THEN 'Road' WHEN 'M' THEN 'Mountain' WHEN 'T' THEN 'Touring' WHEN 'S' THEN 'Other sale items' ELSE 'Not for sale' END, Name FROM Production.Product ORDER BY ProductNumber; GO --示例二 SELECT ProductNumber, Name, "Price Range" = CASE WHEN ListPrice = 0 THEN 'Mfg item - not for resale' WHEN ListPrice < 50 THEN 'Under $50' WHEN ListPrice >= 50 and ListPrice < 250 THEN 'Under $250' WHEN ListPrice >= 250 and ListPrice < 1000 THEN 'Under $1000' ELSE 'Over $1000' END FROM Production.Product ORDER BY ProductNumber ; {/alert}