如何使用SQL

Question

創建主/詳細信息表的摘要視圖我有兩個（簡化）表/班設立這樣的：

public class OrderHeader 
{ 
    public OrderHeader() 
    { 
     Details = new HashSet<OrderDetail>(); 
    } 

    [Key] 
    public int TransactionId { get; set; } 
    public string CustomerName { get; set; } 
    public virtual ICollection<OrderDetail> Details { get; set; } 
} 

public class OrderDetail 
{ 
    [Key] 
    public int DetailId { get; set; } 
    public int ItemId { get; set; } 
    public int QuantityOrdered { get; set; } 
    public int QuantityShipped { get; set; } 
    public int QuantityRemaining { get; set; } 
    public int TransactionId { get; set; } 

    [ForeignKey("TransactionId")] 
    public virtual OrderHeader Header { get; set; } 
} 

我試圖創建一個視圖返回：

1. 的所有細節由OrderHeader通過OrderHeader wher的TransactionId
2. 計數作爲列Number of Details
3. 的細節計數ËQuantityRemaining等於零作爲columnn Completed
4. 通過OrderHeader命名爲Partially Shipped的細節計數，其中QuantityShipped大於零但小於QuantityOrdered

我試圖查詢兩個OrderHeader和OrderDetails表，並試圖讓子查詢我想要的每一列，但我得到了相同的TransactionId多行。當我使用DISTINCT時，選擇的數字與我所知道的正確的數字不符。

雖然承認這是完全可憐，我能得到一個部分，但準確的結果，只有兩列設置：

SELECT 
     TransactionId, 
     COUNT(*) AS [Number of Details] 
    FROM OrderDetails 
    GROUP BY TransactionID 

但我不能把它與其他兩列工作。

Answer 1

像這樣的東西？

SELECT 
    TransactionId, 
    COUNT(*) AS [Number of Details], 
    Sum(CASE WHEN QuantityRemaining = 0 THEN 1 ELSE 0 END) AS [Completed], 
    Sum(CASE WHEN QuantityShipped > 0 AND QuantityShipped < QuantityOrdered THEN 1 ELSE 0 END) AS [Partially Shipped] 
FROM OrderDetails 
GROUP BY TransactionID