left join 左边有数据，右边无数据

 参考了链接： https://blog.csdn.net/chenjianandiyi/article/details/52402011

 

主要是and和where的区别:

 

原Sql:

select a.ID as reqid,(select top 1 Convert(nvarchar(50),jhdatez,111) from CS_OrderPro
where Codeno=a.InvNo and iProductId =a.iProductId)as 'jhdate',
(select top 1 Deptname from UserInfo left join Department on  UserInfo.deptid=Department.Deptid where UserInfo.userid=AuditUserId) as deptname,
(select isnull(SUM(iNum),0) from CS_OrderPro where CS_OrderPro.zid=a.ID and  CS_OrderPro.codeno=a.Invno) as cgnum,
(select top 1 InvNO from CS_OrderPro where CS_OrderPro.zid=a.ID and  CS_OrderPro.codeno=a.Invno) as cginvno,
(select isnull(SUM(CS_InvRecBill.iNum),0) from CS_InvRecBill
left join  CS_OrderPro on CS_InvRecBill.zid=CS_OrderPro.ID
where CS_OrderPro.zid=a.ID and CS_OrderPro.codeno=a.Invno) as rknum,*,
isnull((select sum(pronum) from cs_stock where proid=a.iproductid),0) as kcnum,
comoditiestype from CS_OrderRequise a left join CS_OrderRequiseList c on c.OutCode=a.InvNO
left join B_Products b on b.id=a.iProductID 
left join ComoditiesType on ComoditiesType.typeid=b.typeid    where 1=1 and c.isend=1 and  ComoditiesType.typeid<>336

左连接查询后，最后的where语句过滤了本该显示的数据。

修改过的Sql:

select a.ID as reqid,(select top 1 Convert(nvarchar(50),jhdatez,111) from CS_OrderPro
where Codeno=a.InvNo and iProductId =a.iProductId)as 'jhdate',
(select top 1 Deptname from UserInfo left join Department on  UserInfo.deptid=Department.Deptid where UserInfo.userid=AuditUserId) as deptname,
(select isnull(SUM(iNum),0) from CS_OrderPro where CS_OrderPro.zid=a.ID and  CS_OrderPro.codeno=a.Invno) as cgnum,
(select top 1 InvNO from CS_OrderPro where CS_OrderPro.zid=a.ID and  CS_OrderPro.codeno=a.Invno) as cginvno,
(select isnull(SUM(CS_InvRecBill.iNum),0) from CS_InvRecBill
left join  CS_OrderPro on CS_InvRecBill.zid=CS_OrderPro.ID
where CS_OrderPro.zid=a.ID and CS_OrderPro.codeno=a.Invno) as rknum,*,
isnull((select sum(pronum) from cs_stock where proid=a.iproductid),0) as kcnum,
comoditiestype from CS_OrderRequise a left join CS_OrderRequiseList c on c.OutCode=a.InvNO
left join B_Products b on b.id=a.iProductID
left join ComoditiesType on ComoditiesType.typeid=b.typeid AND   ComoditiesType.typeid<>336   where 1=1 and c.isend=1