SQL查詢計數和標籤如果第一

Question

我正在使用SQL Server管理Studio 2010.

我需要我的查詢來填充列如果記錄包含第一次出現的值。

我的查詢返回的表是巨大的，所以我就用假裝列跨越我的觀點。我的查詢目前返回一個表，看起來像這樣

| ROW | ItemNumber | DateOpen | Status | 
| 1 |  10045 | 5/5/2005 | Open | 
| 2 |  10045 | 5/5/2005 | Open | 
| 3 |  10046 | 5/5/2005 | Open | 
| 4 |  10046 | 5/5/2005 | Open | 
| 5 |  10046 | 5/5/2005 | Open | 

我已經添加了一排指示燈，以查詢以爲這將有助於確定ItemNumber的第一次出現。我需要的是標誌着一個X的新列，如果該記錄是第一次出現。

我有這個迄今爲止

DECLARE @ItemData Table(itemRow BIGINT, itemNumber BIGINT, DateOpen VARCHAR(15), status VARCHAR(15)) 
INSERT INTO @ItemData (itemRow, ItemNumber, DateOpen, Status) 
SELECT Row_Number() OVER(ORDER BY Cm_ItemNumber) AS 'ROW' 
     ,Cm_ItemNumber       AS ItemNumber 
     ,Dates_DateOpen       AS DateOpen 
     ,St_Status        AS Status 
FROM db_Items 
JOIN db_Dates ON Dates_Item = Cm_ItemID 
JOIN db_Status ON St_ID = Cm_StatusID 
Select * from @ItemData 

原因其扔進然後seperately選擇一個表，因爲實際上有查詢工會和更多的東西，當我意識到我需要做的唯一檢查器和它添加到列，我想最簡單的方法將是一個「事後」式的東西，它會進入Select * from @ItemData部分。使用現有查詢作爲第2個熱膨脹係數

Answer 1

我沒有測試過這一點，但它一起我會跟你玩遊戲的線是...
：

With AllData as 
(
SELECT Row_Number() OVER(ORDER BY Cm_ItemNumber) AS 'ROW' 
     ,Cm_ItemNumber       AS ItemNumber 
     ,Dates_DateOpen       AS DateOpen 
     ,St_Status        AS Status 
FROM db_Items 
JOIN db_Dates ON Dates_Item = Cm_ItemID 
JOIN db_Status ON St_ID = Cm_StatusID 
), 
FirstRows as 
(
SELECT Min(ROW) as Row, ItemNumber 
FROM AllData 
GROUP BY ItemNumber 
) 
SELECT 
    ad.*, 
    Case When fr.Row IS NULL then '' else 'X' end as X_Col 
FROM AllData ad LEFT JOIN FirstRows fr 
    ON ad.ROW=fr.Row