select a.*,isnull(b.inNum,0),isnull(b.inSumMoney,0),isnull(c.outNum,0),isnull(c.outSumMoney,0) from bookstore a left join inbase b on a.bookid=b.bookid left join outbase c on a.bookid=c.bookid
加别名:select a.*,isnull(b.inNum,0) inNum,isnull(b.inSumMoney,0) inSumMoney,isnull(c.outNum,0) outNum,isnull(c.outSumMoney,0) outSumMoney from bookstore a left join inbase b on a.bookid=b.bookid left join outbase c on a.bookid=c.bookid
select a.bookid,a.bookname,a.price,a.storenum,isnull(b.inNum,0) inNum,isnull(b.inSumMoney,0) inSumMoney, isnull(c.outNum,0) outNum,isnull(c.outSumMoney,0) outSumMoney from bookstore a join inbase b on a.bookid = b.bookid left join outbase c on a.bookid = c.bookid
isnull(c.outNum,0) outNum,isnull(c.outSumMoney,0) outSumMoney
from bookstore a join inbase b on a.bookid = b.bookid
left join outbase c on a.bookid = c.bookid