分组求和

SELECT COUNT(*) Num, ProductName
FROM (
SELECT  CASE WHEN Params LIKE '%ipad%' THEN 'iPad'
WHEN Params LIKE '%iphone%' THEN 'iPhone'
ELSE 'android' END AS ProductName
FROM AZPLATFORM.DBO.Log_ServiceLog ls
WHERE ServiceCode='PDA_USR_LOGIN' AND
((@StartDate=''OR @StartDate IS NULL OR ls.InvokeTime>=@StartDate) AND (@EndDate=''OR @EndDate IS NULL OR ls.InvokeTime<=@EndDate)) AND
(Params LIKE '%ipad%' OR Params LIKE '%iphone%' OR Params LIKE '%Android%')
) T
GROUP BY ProductName