Q:

Comparing two column List<> based on column one

I'm trying to compare two SQL databases together using C#.
I am storing the List of fields from the first Database in a two column list.
How would I go about matching the two columns from one List to the other? Both databases output Lists with the exact same following two columns (CustNo, CustName).
CustNo is the primary key so I would like to iterate through all CustNo fields and find if the CustName has been changed.
using static ESLBlackBox.MasterReport;

class Program
{
    static void Main(string[] args)
    {
        Program program = new Program();

        var changed = program.ReadNewMasterReport()
            .Where(b => program.ReadOldMasterReport()
            .Any(a => a.custNo == b.custNo && a.custName != b.custName))
            .ToList();

        Console.WriteLine(changed);
    }

    public List<Fields> ReadOldMasterReport()
    {
        SqlDataReader rdr = null;
        SqlConnection conn = new SqlConnection("Data Source=ESLAXSQLDEV1;Initial Catalog=ESLBlackBox;Integrated Security=True");
        SqlCommand cmd = new SqlCommand("select * from Master_Report", conn);
        List<Fields> oldResult = new List<Fields>();

        try
        {
            using (conn)
            {
                conn.Open();
                using (SqlDataReader reader = cmd.ExecuteReader())
                {
                    while (reader != null && reader.Read())
                    {
                        oldResult.Add(new Fields
                        {
                            custNo = Convert.ToString(reader["Service Address Cust No"]),
                            custName = Convert.ToString(reader["Service Address Acct Name"])
                        });
                    }
                }
            }
        }
        finally
        {
            if (rdr != null)
            {
                rdr.Close();
            }

            if (conn != null)
            {
                conn.Close();
            }
        }
        return oldResult;
    }

MasterReport Class
class MasterReport
{
    public class Fields
    {
        public string custNo { get; set; }
        public string custName { get; set; }
    }
}

A:

You can use linq for this:
var changed = listB
    .Where(b => listA
        .Any(a => a.custNo == b.custNo && a.custName != b.custName))
    .ToList();

