以下是我的查询，我得到客户支付最多，付费最少的数据。
但问题是假设客户A支付最多，并且如果有很多客户，它会与客户A重复3到4条记录。
我需要客户付款最少到最低付款，之后客户支付最多的付款。
需要包括客户无法做到的分组。
select
a.custcode, a.dono, b.dolnno, b.item, b.itemdesc,
isnull(a.ordertype,'') ordertype,
a.custname, a.CollectionDate,
CAST((SUBSTRING(a.CollectionDate, 7, 4) + SUBSTRING(a.CollectionDate, 4, 2) + SUBSTRING(a.CollectionDate, 1, 2)) AS date) AS trandate,
isnull(a.jobnum,'') jobnum,
isnull(a.Remark1,'') as remarks,
b.lnstat, isnull(b.qtyor,0) qtyor,
isnull(b.qtypick, 0) qtypick, isnull(b.qtyis, 0) qty,
isnull(b.unitprice, 0) unitprice, b.crat,
ISNULL(qtyor * b.unitprice, 0) ordPrice,
ISNULL(qtyis * b.unitprice, 0) issPrice,
isnull(deliverydate, '') deliverydate,
isnull(timeslots, '') deliverytime,
isnull(c.prd_brand_id, '') as prd_brand_id,
isnull(c.prd_cls_id, '') as prd_cls_id,
isnull(c.itemtype, '') as itemtype,
isnull(a.status_id, '') as status_id,
isnull(a.OUTBOUND_GST, 0) as Tax
from
[test_dohdr] a,[test_dodet] b,[test_ITEMMST]c
where
a.dono = b.dono
and b.ITEM = c.item
and ISNULL(CollectionDate, '') <> ''
AND CAST((SUBSTRING(a.CollectionDate, 7, 4) + '-' + SUBSTRING(a.CollectionDate, 4, 2) + '-' + SUBSTRING(a.CollectionDate, 1, 2)) AS date) >= '2014-05-01'
and ISNULL(CollectionDate, '') <> ''
AND CAST((SUBSTRING(a.CollectionDate, 7, 4) + '-' + SUBSTRING(a.CollectionDate, 4, 2) + '-' + SUBSTRING(a.CollectionDate, 1, 2)) AS date) <= '2015-05-07'
order by
(qtyis * b.unitprice) DESC