from and select in c# .net?

Question

Can anyone Please tell me how to specify the particular column in the select statement given below:

var combinedrows = from dt1 in DsResults.Tables[0].AsEnumerab         


        

Answer 1

Just read your comment. I think what you want is not a join but the following:

var combinedrows = 
    from dt1 in DsResults.Tables[0].AsEnumerable()
    from dt2 in DsResults.Tables[1].AsEnumerable()
    where dt1.Field<string>("MethodName") equals dt2.Field<string>("MethodName")
    select new { dt1, dt2 };

It returns ony rows from both tables that have the same "MethodName".

Answer 2

If you want to specify which columns you want to select, you should try changing

combinedrows = from dt1 in DsResults.Tables[0].AsEnumerable() join
dt2 in DsResults.Tables[1].AsEnumerable() on dt1.Field("MethodName") equals
dt2.Field("MethodName") select new { dt1, dt2 };

in

combinedrows = from dt1 in DsResults.Tables[0].AsEnumerable() join
dt2 in DsResults.Tables[1].AsEnumerable() on dt1.Field("MethodName") equals
dt2.Field("MethodName") select new 
{
     dt1.columnName;
     dt2.columnName2;
     dt2.columnName3;
     etc.
}

Hope this what you were looking for.

You can have a look at the LinQ-CheatSheet

Answer 3

@Prem: Use this code its working fine, check it out.

var combinedrows = from dt1 in DsResults.Tables[0].AsEnumerable()
                              join dt2 in DsResults.Tables[1].AsEnumerable() on        dt1.Field<string>("MethodName") equals dt2.Field<string>("MethodName")
                           select new { sp = dt1.Field<string>("Tab1_col1"), Method = dt1.Field<string>("MethodName"), _class = dt1.Field<string>("Class"),
                                        BLLMethod = dt1.Field<string>("Tab2_col2")
                           }; 


        DataTable finaldt = new DataTable("FinalTable");
        finaldt.Columns.Add(new DataColumn("sp", typeof(string)));
        finaldt.Columns.Add(new DataColumn("Method", typeof(string)));
        finaldt.Columns.Add(new DataColumn("Class", typeof(string)));
        finaldt.Columns.Add(new DataColumn("BLLMethod", typeof(string)));
        DataRow newrow = finaldt.NewRow();           
        foreach (var row in combinedrows)
        {
            DataRow dr = finaldt.NewRow();
            dr["sp"] = row.sp;
            dr["Method"] = row.Method;
            dr["Class"] = row._class;
            dr["BLLMethod"] = row.BLLMethod;
            finaldt.Rows.Add(dr);
        }

Answer 4

Not sure what your question is... The linq query is a regular join between dsResults.Tables[0] and dsResults.Tables[1] based on the MethodName field.

What are you trying to do?

Answer 5

Well, it's not really clear what you want, but something like this, perhaps?

var combinedRows = from dt1 in DsResults.Tables[0].AsEnumerable()
                   join dt2 in DsResults.Tables[1].AsEnumerable()
                     on dt1.Field<string>("MethodName") 
                     equals dt2.Field<string>("MethodName")
                   select new { MethodName = dt1.Field<string>("MethodName"),
                                Foo = dt2.Field<string>("Foo"),
                                Bar = dt1.Field<int>("Bar") };