SQL帶回材質名稱

Question

下面的代碼是我創建的查詢的結果，除了一件事情之外，它都可以正常工作。我有材質ID的物料名稱：

1 = bath 
2 = sink 
3 = toilet 

下面的作品，但顯示宿每種材料

Select cu.FName + ' ' + cu.SName as 'Name', 
cu.Address1 + ', ' + cu.Address2 + ', ' + cu.Address3 as 'Dispatch Address', 
cu.PostCode, 
co.DateOrdered, 
co.Material1, 
ma.MaterialName, 
co.material2, 
ma.MaterialName, 
ma.Price as 'Item Price' 
from Customers cu 
left join CustomerOrder co on co.CustomerID = cu.CustomerID 
left join ItemOrder it on it.OrderID = co.OrderID 
left join Materials ma on ma.MaterialID = co.Material1 
or co.material2 = ma.MaterialItemID or co.material3 = ma.MaterialItemID 

它顯示如下（只是材料列停止混亂）

Material1 | MaterialName | Material2 | Material2Name | Material3 | Material3Name 
    1   Sink   2   Sink   3    Sink 

任何人都可以幫忙嗎？

Answer 1

有幾個方法可以做到這一點，包括使用materials表上多次JOIN得到結果：

Select cu.FName + ' ' + cu.SName as 'Name', 
    cu.Address1 + ', ' + cu.Address2 + ', ' + cu.Address3 as 'Dispatch Address', 
    cu.PostCode, 
    co.DateOrdered, 
    co.Material1, 
    ma1.MaterialName Material1Name, 
    co.material2, 
    ma2.MaterialName Material2Name, 
    ma1.Price as 'Item Price', 
    co.material3, 
    ma3.MaterialName Material3Name 
from Customers cu 
left join CustomerOrder co 
    on co.CustomerID = cu.CustomerID 
left join ItemOrder it 
    on it.OrderID = co.OrderID 
left join Materials ma1 
    on ma1.MaterialID = co.Material1 
left join Materials ma2 
    on co.material2 = ma2.MaterialItemID 
left join Materials ma3 
    on co.material3 = ma3.MaterialItemID