我在mysql查询中使用这些代码
select c1.date,sum(SELECT IFNULL(cx.purchase-cx.sold,0))+MAX(p.openqty) as opening) as date,SELECT IFNULL(a.qty,0) as purchase,SELECT IFNULL(b.qty,0) as sold from arrival a FULL JOIN,b.date) as date,SELECT IFNULL(a.qty,0) as purchase,