C# Using Linq to join 2 tables with 2 same columns

Question

I want to join 2 tables, which they have 2 same columns. I have tried this but got error with on new {} equals new {}.

My Code:

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
    };

Tim Schmelter · Accepted Answer · 2012-09-21 10:50:51Z

4

Try...

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();

answered Sep 21, 2012 at 10:50

Tim Schmelter

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Comments

Jan P. · Accepted Answer · 2012-09-21 10:51:15Z

1

Try to name the properties of your anonymous types.

From MSDN:

Because the Equals and GetHashCode methods on anonymous types are defined in terms of the Equals and GetHashcode methods of the properties, two instances of the same anonymous type are equal only if all their properties are equal.

answered Sep 21, 2012 at 10:51

Jan P.

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