How to create a summary view of Master/Detail Tables using SQL

Question

I have two (simplified) tables/classes set up like this:

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; }
}

I am trying to create a view to return:

1. The TransactionId
2. A count of all details by OrderHeader as column Number of Details
3. A count of details by OrderHeader where QuantityRemaining equals zero as columnn Completed
4. A count of details by OrderHeader named Partially Shipped where QuantityShipped is greater than zero but less than QuantityOrdered

I have tried querying both the OrderHeader and the OrderDetails tables and trying to make sub queries for each column I wanted but I wind up getting multiple lines with the same TransactionId . And when I use the DISTINCT select the numbers are off from what I know to be correct.

While admitting this is utterly pitiful, I can get a partial but accurate result set with only two columns:

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

But I can not get it working with the other two columns.

Answer 1

Something like this ?

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