SQL最新日期記錄

Question

更新：現在正確地爲每個項目提供最近交付的供應商名稱。我現在遇到的問題是它沒有提取沒有先前交付的記錄（空白dlvry_dt）。有誰知道如何解決這一問題？

非常感謝您的幫助！

;WITH Items As(
Select 
a.bin, a.item, d.item_description As 'Vintage', a.min_reorder, 
c.minor_item_class, c.minor_class_description, a.qty_available, 
a.reorder_threshold As 'Par', a.avg_unit_cost, 
a.qty_available*a.avg_unit_cost As 'Valuation', e.dlvry_dt, g.supplier, 
g.supplier_name, 
RowNum = ROW_NUMBER() OVER(PARTITION BY a.item ORDER BY dlvry_dt DESC) 

from argus.STORE_INVENTORY a, argus.MAJOR_ITEM_CLASS b, 
argus.MINOR_ITEM_CLASS c, argus.ITEM_MASTER d, argus.DELIVERY e 

inner join argus.delivery_line_item f 
on e.delivery = f.delivery 
and e.purchase_order = f.purchase_order 
and e.customer = f.customer 
and e.store = f.store 
and e.supplier = f.supplier 
full outer join argus.supplier g 
on e.supplier = g.supplier 


where a.customer = 10005 
and a.store = 1 
and d.item = a.item 
and b.major_item_class = c.major_item_class 
and d.minor_item_class = c.minor_item_class 
and (b.major_item_class = 15 or b.major_item_class = 17 or b.major_item_class = 14) 
and (c.minor_item_class = 830 or c.minor_item_class = 175 or c.minor_item_class = 880 or c.minor_item_class = 661 or c.minor_item_class = 651 or c.minor_item_class = 785 or c.minor_item_class = 716 or c.minor_item_class = 810 or c.minor_item_class = 850 or c.minor_item_class = 885 or c.minor_item_class = 998 or c.minor_item_class = 840 or c.minor_item_class = 855 or c.minor_item_class = 280) 
and f.line_item_status <> 'D' 
and e.customer = 10005 
and e.store = 1 
and f.item = a.item 
--and (c.minor_item_class = 176 or c.minor_item_class = 651 or c.minor_item_class = 661 or c.minor_item_class = 716 or c.minor_item_class = 810 or c.minor_item_class = 830 or c.minor_item_class = 840 or c.minor_item_class = 850 or c.minor_item_class = 855 or c.minor_item_class = 885 or c.minor_item_class = 998) 
Group By c.minor_class_description, a.bin, a.item, d.item_description, a.min_reorder, a.qty_available, a.reorder_threshold, a.avg_unit_cost, c.minor_item_class, e.dlvry_dt, g.supplier, g.supplier_name 

) 
Select bin, item, Vintage, min_reorder, minor_item_class, minor_class_description, qty_available, Par, avg_unit_cost, Valuation, dlvry_dt, supplier, supplier_name 
From Items 
Where RowNum =1 
Order By minor_class_description 

Answer 1

一種方法是使用CTE（公用表表達式）。

使用此CTE，您可以按照某些條件（即，您的Item）對數據進行分區，並且SQL Server編號的所有行都從1開始，針對每個「分區」，按照某些標準排序。

因此，嘗試這樣的事：

;WITH Items AS 
(
    SELECT 
     Item, Vintage, Qty, DeliveryDate, 
     RowNum = ROW_NUMBER() OVER(PARTITION BY Item ORDER BY DeliveryDate DESC) 
    FROM 
     dbo.YourTableHere -- possibly several JOINs 
    WHERE 
     ...... 
) 
SELECT 
    Item, Vintage, Qty, DeliveryDate 
FROM 
    Items 
WHERE 
    RowNum = 1 

在這裏，我只選擇了「第一」爲每個「分區」項（即每個Item） - 由降DeliveryDate有序。

這是否接近你要找的？

更新：，如果你想在DeliveryDate可能NULL條目，也可以使用類似

 RowNum = ROW_NUMBER() OVER(PARTITION BY Item ORDER BY ISNULL(DeliveryDate, '99991231' DESC) 

轉NULL爲31日 - 12月9999日期 - 那些永遠是第一位的當按降序排列時。