如何在基於子類型的查詢中選擇表？

我有4個表，交易，訂單 - 超，然後Site_Orders和Product_Orders子類型如何在基於子類型的查詢中選擇表？

[Transactions] 
id PK 
Orders_id [FK Orders.orders_id] 

[Orders] 
Orders_id PK 
Orders_type 

[Site_Orders] 
Orders_id [FK Orders.orders_id] 
== other data == 

[Product_Orders] 
Orders_id [FK Orders.orders_id] 
== other data ==

我的問題是，如何創建一個連接語句，將拉動交易和關聯，並搶在正確的信息子類型表？或者我將不得不使用PHP來檢查子類型並在那裏完成邏輯？

感謝

來源

2010-09-14 William Smith

SELECT ... 
FROM Orders o 
JOIN Transactions t ON t.Orders_id = o.Orders_id 
LEFT OUTER JOIN Site_Orders so 
    ON so.Orders_id = o.Orders_id AND o.Orders_type = 'S' 
LEFT OUTER JOIN Product_Orders po 
    ON po.Orders_id = o.Orders_id AND o.Orders_type = 'P'

來源

2010-09-14 23:49:37

如何在基於子類型的查詢中選擇表？

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