SQL查詢來獲取所有不同的項目最新記錄表中的

Question

我定義的所有銷售的表像：

mysql> describe saledata; 
+-------------------+---------------------+------+-----+---------+-------+ 
| Field    | Type    | Null | Key | Default | Extra | 
+-------------------+---------------------+------+-----+---------+-------+ 
| SaleDate   | datetime   | NO |  | NULL |  | 
| StoreID   | bigint(20) unsigned | NO |  | NULL |  | 
| Quantity   | int(10) unsigned | NO |  | NULL |  | 
| Price    | decimal(19,4)  | NO |  | NULL |  | 
| ItemID   | bigint(20) unsigned | NO |  | NULL |  | 
+-------------------+---------------------+------+-----+---------+-------+ 

我需要得到最後的銷售價格對所有項目（如價格可能改變）。我知道我可以運行像查詢：

SELECT price FROM saledata WHERE itemID = 1234 AND storeID = 111 ORDER BY saledate DESC LIMIT 1 

不過，我希望能夠獲得最後的銷售價格（對ItemID s的存儲在一個單獨的項目表）中的所有項目，並把它們插入到一個單獨的表。我怎樣才能得到這些數據？我試過這樣的查詢：

SELECT storeID, itemID, price FROM saledata WHERE itemID IN (SELECT itemID from itemmap) ORDER BY saledate DESC LIMIT 1 

然後將其封裝到插入，但它沒有得到正確的數據。是否有一個查詢我可以運行，以獲得最後的價格爲每個項目，並插入到表中這樣定義：

mysql> describe lastsale; 
+-------------------+---------------------+------+-----+---------+-------+ 
| Field    | Type    | Null | Key | Default | Extra | 
+-------------------+---------------------+------+-----+---------+-------+ 
| StoreID   | bigint(20) unsigned | NO |  | NULL |  | 
| Price    | decimal(19,4)  | NO |  | NULL |  | 
| ItemID   | bigint(20) unsigned | NO |  | NULL |  | 
+-------------------+---------------------+------+-----+---------+-------+ 

Answer 1

這是頻繁出現堆棧溢出的最大正每組問題。

INSERT INTO lastsale (StoreID, Price, ItemID) 
    SELECT s1.StoreID, s1.Price, s1.ItemID 
    FROM saledata s1 
    LEFT OUTER JOIN saledata s2 
    ON (s1.Itemid = s2.Itemid AND s1.SaleDate < s2.SaleDate) 
    WHERE s2.ItemID IS NULL;