--简单caseuse Northwindgoselect top 10 orderID,orderID %10 AS 'Las Digit',position=case orderID % 10when 1 then'First'when 2 then 'Second'When 3 then 'Third'When 4 then 'Fourth'else 'something else'endfrom Ordersuse Northwindgoselect top 10 orderid %10 AS "LAST NIGHT",Productid,"How Close?"= case orderid % 10when productid then 'Exact Match!'when productid-1 then 'within 1'when productid+1 then 'within 1'else 'More han one apart'endfrom [order Details]where productID<10order by orderID desc

--搜索case--搜索case语句和简单case 语句非常相同，只有两个不同点--1.没有输入表达式（case和when之间）--2.when表达式必须为布尔值use Northwindgoselect top 10 orderID %10 as "Last Digit",productID,"How Close?"=casewhen (OrderId % 10)<3 then 'Ends with less than three'when productid=6 then 'ProductId is 6'--ABS取绝对值when ABS(orderid %10 -productid)<=1 then 'within 1'else 'Mroe than one apart'endfrom [Order Details]where ProductID<10order by OrderID desc