大家给看看这个sql语句，小弟我实在看不懂,关键是LEFT OUTER JOIN,多谢了

大家给看看这个sql语句，我实在看不懂,关键是LEFT OUTER JOIN,谢谢了
SELECT   dbo.wuliu_huopin.bianhao   AS   pinming,dbo.wuliu_huopin.mingcheng   AS   mingcheng,dbo.wuliu_huopin.sp_xinhao   AS   sp_xinhao,   dbo.wuliu_huopin.lei   AS   lei,shuliang=case   when   sum(shuliang)   is   null   then   0   else   sum(shuliang)   end,dbo.wuliu_huopin.danwei,dbo.wuliu_huopin.xiaoshoujia   FROM   dbo.wuliu_huopin   LEFT   OUTER   JOIN   dbo.wuliu_ruku   ON   dbo.wuliu_huopin.bianhao   =   dbo.wuliu_ruku.pinming   WHERE   (dbo.wuliu_huopin.shangpingbj   =   1   and   dbo.wuliu_huopin.lei= "&leiid& ")   group   by   bianhao,mingcheng,sp_xinhao,wuliu_huopin.lei,wuliu_huopin.danwei,xiaoshoujia

------解决方案--------------------
呵呵，这么写SQL语句的人真的不是一般的笨。
这样写完后自己看都费劲，就别说别人了。。。

给表起个别名就完了，非得整个dbo.wuliu_huopin

这是一个汇总的联合查询。。。

取出wuliu_huopin表中bianhao,mingcheng,sp_xinhao,lei,danwei,xiaoshoujia 这几列并对
shuliang进行求和。
表wuliu_huopin和表wuliu_ruku左连接条件是wuliu_huopin.bianhao =dbo.wuliu_ruku.pinming和WHERE (dbo.wuliu_huopin.shangpingbj = 1 and dbo.wuliu_huopin.lei= "&leiid& ")
后面的group by 是分组滤重的。。。