將SQL語句轉換為Linq？

Question

我有一個名為Outweigh的表，它有大約50個字段。 我需要創建一個Linq查詢，就像這個SQL查詢一樣。

SELECT DISTINCT Product, 
   Medication, 
   SUM(NettWeight) as NettWt, 
   COUNT(DISTINCT CustCode) as Customer, 
   COUNT(DISTINCT DktNo)as DktNo
FROM outweigh
GROUP BY Product, Medication
ORDER BY Product, Medication

結果如下：

我寫了一些代碼如下，效率不高。

lstOutWeigh = dbContext.Outweighs
                       .Where(o => o.DateOut >= StartDate && o.DateOut <= EndDate)
                       .ToList();

  var k = from t in lstOutWeigh select new {t.Product,t.Medication,t.NettWeight};
  var l  = from t in k
           group t by new { t.Product, t.Medication } into g
           select new someclass
           {
               prod =g.Key.Product,
               med = g.Key.Medication,
               tonnes = (double) g.Sum(x => x.NettWeight),
               count = g.Count()
           };

有什么建議么？

Answer 1

正如有人提到的， http：//sqltolinq.com/效果很好。

http://www.linqpad.net/也是另一個很棒的工具（我/我個人在工作的地方使用）可以幫助你在這些類型的語句之間進行轉換 - 即使你喜歡使用Lambda表達式 - 在我的意見是使用LINQ查詢的最簡單方法之一。

Answer 2

就像是，

db.Outweighs.GroupBy(ow => new { ow.Product, ow.Medication })
    .OrderBy(g => g.Key)
    .Select(g => new
        {
            g.Key.Product,
            g.Key.Medication,
            NettWt = g.Sum(ow => ow.NettWeight),
            Customer = g.Select(ow => ow.CustCode).Distinct().Count(),
            DktNo = g.Select(ow => ow.DktNo).Distinct().Count()
        })

等同於您在問題中提供的SQL。 但是，你提出的Linq-To-Sql並不匹配。

Answer 3

     var t = (from  p in Context.outweigh
              group p by new {p.Product,p.Medication}  into g
              select new {Product= t.Product,Medication=t.Medication, NettWt = g.Sum(x => x.NettWeight),Customer=g.Count())
             .Distinct().orderby(new {p.Product, p.Medication});