C# 使用 Linq 连接具有 2 个相同列的 2 个表

Question

我想连接 2 个表，它们有 2 个相同的列。我试过这个，但在新 {} 等于新 {} 时出错。

我的代码:

var results = from table1 in table.AsEnumerable()
    join table2 in comment.AsEnumerable()
    //Comment
    on new {table1.Field<string>("SignalName"), table1.Field<int?>("MessageID")} 
    equals new {table2.Field<string>("SignalName"), table2.Field<int?>("MessageID")} 

    into prodGroup
    from table3 in prodGroup.DefaultIfEmpty()

    select new
    {
       // something is there
    };

Answer 1

尝试...

var results = from r1 in table.AsEnumerable()
              join r2 in comment.AsEnumerable()
              on new {
                        signal=r1.Field<string>("SignalName"), 
                        message=r1.Field<int?>("MessageID")
               } 
              equals new {
                        signal=r2.Field<string>("SignalName"), 
                        message=r2.Field<int?>("MessageID")
              } into prodGroup
              from r3 in prodGroup.DefaultIfEmpty();