SQL高手帮帮忙啊，急坏了,好心人先谢了(25分)

入库表 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;出库表 &nbsp; <br>入库日期 &nbsp; &nbsp;商品 &nbsp;数量 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 出库日期 &nbsp; &nbsp;商品 &nbsp;数量<br>2008.12.12 &nbsp;牙膏 &nbsp; 1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2008.12.15 &nbsp;牙刷 &nbsp;1<br>2008.12.12 &nbsp;牙刷 &nbsp; 1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2008.12.15 &nbsp;牙膏 &nbsp;1<br>2008.12.13 &nbsp;牙刷 &nbsp; 1<br><br>怎样用SQL语句列出所有商品的库存数量？ &nbsp;<br>select b.商品,sum(b.數量) as 庫存 from <br>(select 商品,數量 from 入庫表<br>union &nbsp;all <br>select 商品,數量*-1 as數量 from 出庫表) b group by 商品 &nbsp;<br>把上面的SQL语句改成interbase语句怎么写啊？？interbase不支持 from 后带(select ..)

interbase没有用过，试试下面的语句好不好用吧<br><br>select a.商品, sum(a.数量) - isnull(sum(b.数量), 0)<br>from 入库表 a left join 出库表 b<br>on a.商品 = b.商品<br>group by a.商品

给括号内的select语句建立视图，然后对视图select

再不行就用临时表！！！！