按組訪問SQL查詢

Question

我有一個包含TaxID，Price，DatePurchaced的表，每個TaxId多次顯示不同的Price和DatePurchaced，我想按Sum（Price）按TaxId分組，並顯示最后一個DatePurchaced，我也想用Count（TaxID）列嘗試一下查詢，但總是向我顯示一條記錄，記錄最新的日期

Answer 1

declare @tbl as table (TaxID int, Price money, DatePurchaced datetime)

insert into @tbl (TaxID, Price, DatePurchaced) values (1, 10.5, '2015-03-05 10:25:23');
insert into @tbl (TaxID, Price, DatePurchaced) values (1, 13, '2015-03-09 10:25:23');
insert into @tbl (TaxID, Price, DatePurchaced) values (1, 7, '2015-03-20 10:25:23');
insert into @tbl (TaxID, Price, DatePurchaced) values (2, 10.5, '2015-07-05 10:25:23');
insert into @tbl (TaxID, Price, DatePurchaced) values (2, 8, '2015-07-08 10:25:23');


select  t.TaxId as TaxID, 
        count(t.TaxId) as Cnt,
        sum(t.Price) as TotalPrice,
        max(t.DatePurchaced) as LastPurchaseDate
from @tbl as t
group by t.TaxId