这是不是最基础的三个表关联吗。。。

select 

c.orgcode as 组织,

b.barcode as 条码,

a.pinlei as 品类,

a.plucode as 商品编码,

a.pluname as 名称, 

nvl(b.xscount,0) as 销量,

nvl(b.hxtotal,0) as 销售额,

c.kccount as 库存 

from plucaiji  a 

left join (select ts.orgcode 

,ts.barcode

, ts.plucode

,sum(ts.xscount) as xscount

,sum(ts.hxtotal) as hxtotal 

from rhz_xsmx ts 

where ts.rptdate between '2021-12-18' and '2021-12-31' 

GROUP BY ts.orgcode,ts.plucode

,ts.barcode ,ts.pluname ) b on a.plucode=b.plucode 

left join ( 

select m.orgcode

,n.plucode

,n.pluname

, sum(m.KcCount) as kccount 

from tStkLsKc m 

,tSkuPlu n 

where m.PluID = n.PluID

and m.orgcode in ('0001') 

group by m.orgcode

,n.plucode

,n.pluname

) c on b.orgcode=c.orgcode and a.plucode=c.plucode 

where 1=1

and a.pinlei in ('福临门') 

order by a.plucode

这里的限制移动到这个箭头的后面，不要放在最外面where 

select 

c.orgcode as 组织,

b.barcode as 条码,

a.pinlei as 品类,

a.plucode as 商品编码,

a.pluname as 名称, 

nvl(b.xscount,0) as 销量,

nvl(b.hxtotal,0) as 销售额,

c.kccount as 库存 

from (

select 

plucode,

pluname

,pinlei 

from plucaiji) a 

left join (select ts.orgcode 

,ts.barcode

, ts.plucode

,sum(ts.xscount) as xscount

,sum(ts.hxtotal) as hxtotal 

from rhz_xsmx ts where 

ts.rptdate between '2021-12-18' and '2021-12-31' 

GROUP BY ts.orgcode,ts.plucode

,ts.barcode ,ts.pluname ) b on a.plucode=b.plucode 

left join ( 

select m.orgcode

,n.plucode

,n.pluname

, sum(m.KcCount) as kccount 

from tStkLsKc m 

,tSkuPlu n where m.PluID = n.PluID

and m.orgcode in ('0001')  

group by m.orgcode

,n.plucode

,n.pluname

) c on b.orgcode=c.orgcode and a.plucode=c.plucode 

where 1=1

and a.pinlei in ('福临门') 

order by a.plucode