c# - Linq 查询计数和 GroupBy

Question

谁能告诉我如何在 Linq 中执行此 SQL 查询？

SELECT [id], COUNT(*) FROM [data].[dbo].[MyTable] GROUP BY [id]

Answer 1

您可以尝试这种方法：

 var res = ctx.MyTable  // Start with your table
    .GroupBy(r => r.id) / Group by the key of your choice
    .Select( g => new {Id = g.Key, Count = g.Count()}) // Create an anonymous type w/results
    .ToList(); // Convert the results to List

Answer 2

你可以试试这个

var res = from r in MyTable 
          group p by r.id into grouped
          select new {id = g.key, total = g.Count()};

然后，当你必须使用它时，只需ToList() 在select new. 我不必在Visual Studio 2010这里尝试，但我认为它会起作用