Question

I am trying to run over all the fields of a row returned by ExecuteReader(), see here:

SqlCommand cmd = new SqlCommand(@"select * from People;", conn);
rdr = cmd.ExecuteReader();
while (rdr.Read()) 
{
    foreach (Object i in rdr) 
    {
        Console.WriteLine(i.ToString() + " ");
    }
}

This outputs to the console:

System.Data.Common.DataRecordInternal

What should I put instead of object, as some of the fields are numerical (probably being internally cast to int) and some arevarchar (probably being internally cast to string). I did try string but that throws an error on the numerical fields. Likewise, using type var won’t compile.

Thanks.

Answer 1

When you iterate foreach (object i in rdr) you are iterating the rows, not the columns. See the documentation for the data reader’s GetEnumerator() method. That’s why the ToString override is returning System.Data.Common.DataRecordInternal: you’re calling ToString() on the whole data record, not just one of its values.

To iterate the values of the reader’s current row, call the GetValues() method instead; this returns an array of objects corresponding to populates an array of objects with the values for the current row:

while (rdr.Read())  
{
    var items = new object[rdr.FieldCount];
    rdr.GetValues(items);
    foreach (object i in items)  
        Console.WriteLine(i.ToString() + " "); 
}