MySQL查詢與集團

Question

我玩過很多不同的查詢，但一直沒有找到正確的語法爲這個項目..我真的希望有人可以理解我的爛攤子。

我有一個訂單表，每個訂單一行，每行都包含客戶編號，採購訂單編號和訂單日期等信息。採購訂單號碼可以綁定到一個或多個訂單，這是我迷路的地方。我試圖創建一個包含客戶編號，PO＃，最早訂單日期和最後一個訂單日期（根據PO＃分組）的單個行的查詢。

任何指向正確的方向將非常感謝！

Answer 1

這將獲得訂單和範圍的東西...

select 
     o.PONumber, 
     o.CustomerID, 
     count(*) as TotalOrders, 
     min(o.OrderID) as FirstOrder, 
     min(o.OrderDate) as FirstOrderDate, 
     max(o.OrderID) as LastOrder, 
     max(o.OrderDate) as LastOrderDate 
    from 
     Orders o 
    group by 
     o.PONumber, 
     o.CustomerID 

Answer 2

試試這個：

SELECT 
    o1.`customer_number` as 'customer', 
    o1.`po` as 'po_number', 
    (
     SELECT 
      MIN(`date`) 
     FROM 
      `orders` 
     WHERE 
      `id` = o1.`id` 
    ) as 'earliest_date' 
FROM 
    `orders` o1 
GROUP BY 
    o1.`po` 

希望有所幫助。

Answer 3

SELECT o.custumer, o.po_number, o.order_count, max.max_date, min.min_date 
FROM 
(
SELECT o.'costumer_number' as 'custumer', o.'po' as 'po_number', count('order_number') as 'order_count' 
FROM 'orders' o 
GROUP BY o.'costumer_number', o.'po' 
) o 
INNER JOIN (
    SELECT o.'costumer_number' as 'custumer', o.'po' as 'po_number', MAX('order_date') as 'max_date' 
    FROM 'orders' o 
    GROUP BY o.'costumer_number', o.'po'  
) max ON o.'customrer' = max.'costumer' and o.'po_number' = max.'po_number' 
INNER JOIN (
    SELECT o.'costumer_number' as 'custumer', o.'po' as 'po_number', min('order_date') as 'min_date' 
    FROM 'orders' o 
    GROUP BY o.'costumer_number', o.'po'  
) min ON o.'customrer' = min.'costumer' and o.'po_number' = min.'po_number' 
ORDER BY 1,2 

這shold清除出來你要哪`PO＃`