在ASP.NET MVC中將SQL查詢到LINQ

Question

請任何人可以幫助我將此SQL查詢寫入Linq。 我努力了..

這是我的SQL查詢

select  o.OrderID,o.Nature,o.Date,od.TotalPrice,os.OrderStatus,lo.FirstName,lo.EmailAddress,lo.PhoneNumber
from [dbo].[Order] o
    inner join [dbo].[tbl_OrderDetails] od on  od.OrderID = o.OrderID
    inner join [dbo].[tbl_OrderHistory] oh on oh.OrderID = o.OrderID
    inner join [dbo].[tbl_Login] lo on o.UserID = lo.UserID
    inner join dbo.tbl_OrderStatus os on oh.OrderStatusID= os.OrderStatusID
group by o.OrderID,o.Nature,od.TotalPrice,o.Date,os.OrderStatus,lo.FirstName,lo.EmailAddress,lo.PhoneNumber

這是我的嘗試

public override orderDetailModel orderDetails(int id)
{
    var results = from o in obj.Orders
        join od in obj.tbl_OrderDetails on o.OrderID equals od.OrderID
        join oh in obj.tbl_OrderHistory on o.OrderID equals oh.OrderID
        join l in obj.tbl_Login on o.UserID equals l.UserID
        join os in obj.tbl_OrderStatus on oh.OrderStatusID equals os.OrderStatusID
        where (od.OrderID == id)
        group o by new { o.Nature, o.OrderID } into 
        select new orderDetailModel
        {
            OrderID = o.OrderID,
            OrderStatus = os.OrderStatus,
            Date = o.Date,
            DeliveryNature = o.Nature,
            EmailAddress = l.EmailAddress,
            FirstName = l.FirstName,
            PhoneNumber = l.PhoneNumber,
            TotalPrice = od.TotalPrice
        };
    //group o by new {o.OrderID};
    orderDetailModel data = (orderDetailModel)results.FirstOrDefault();
    return data;
}

但這是錯誤的查詢，它不能正常工作，請幫助我

Answer 1

您需要更正group by子句，就像在SQL查詢中這樣：

group new { o, l } by new {  o.OrderID,o.Nature,od.TotalPrice,o.Date,os.OrderStatus,
                             l.FirstName, l.EmailAddress,l.PhoneNumber } into g
                      select new orderDetailModel
                      {
                          OrderID = g.Key.OrderID,
                          OrderStatus = g.Key.OrderStatus,
                          Date = g.Key.Date,
                          ..and so on
                      };

由於您需要在兩個表Order ＆ tbl_Login上進行分組， tbl_Login您必須首先將它們投影為匿名類型group new { o, l }然后指定所有分組，最后在投影時使用Key來獲取各個項目。

Answer 2

我想實際上，SQL查詢也不正確。 我只是使用SELECT DISTINCT ...而不是對所有列進行分組。

無論如何，首先要做的是：

1. 檢查數據庫設計是否正確。 據我所知，如果您將表與他們的ID一起加入，我不明白為什么需要對所有數據進行分組。 如果您有重復項，則可能是數據庫設計中的錯誤。

2. 如果您不能更改數據庫或對此感到滿意，請使用以下LINQ方法：

    var distinctKeys = allOrderDetails.Select(o => new { o.OrderID, o.Nature, o.TotalPrice, o.Date,o.OrderStatus,o.FirstName, o.EmailAddress,o.PhoneNumber }).Distinct(); var joined = from e in allOrderDetails join d in distinctKeys on new { o.OrderID, o.Nature,o.TotalPrice, o.Date,o.OrderStatus, o.FirstName, o.EmailAddress, o.PhoneNumber } equals d select e; joined.ToList(); // gives you the distinct/grouped list