Question

This query just doesnt seem to be very happy. Any ideas anyone?

var results = from a in previousQuery
              join b in dtCounties.AsEnumerable()
              on new { a.CountyCode, a.StateCode } equals new { 
                  b.Field<string>("COUNTYCODE"),
                  b.Field<string>("StateCode") 
              }
              where b.Field<bool>("TrueOrFalse") == true
              select new
              {
                  CountyCode = a.CountyCode,
                  TrueOrFalse= b.Field<bool>("TrueOrFalse"),
                  Sum= a.Sum
              };

The error I get is

“Invalid anonymous type member declarator. Anonymous type members must be declared with a member assignment, simple name or member access.”

for the 2 columns in the right hand side of the join (ie b.Field<string>("COUNTYCODE") and b.Field<string>("StateCode")).

Answer 1

This is just a C# syntax issue, not LINQ itself. Consider the following:

var a = new { "1" };     // Error
var a = new { a = "1" }; // OK

Just to clarify, here is the result of the above:

on new { cc = a.CountyCode, sc = a.StateCode }
    equals new { cc = b.Field<string>("COUNTYCODE"),
                 sc = b.Field<string>("StateCode") }