select?b.股票名稱,sum(b.收益)?已收益,sum(b.持有數量)?當前持有數量?from?(select?股票名稱,(case?when?a.投資行為='買'?then?a.交易數量?else?(-1)*a.交易數量?end)?持有數量,(case?when?a.投資行為='買'?then?(-1)*a.交易金額?else?a.交易金額?end)?收益?from?a)?b?group?by?b.股票名稱