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Execute complicated SQL query

using System; using System.Data; using System.Data.OleDb; public class ExtractInfo {      public static void Main () {     String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";    OleDbConnection con = new OleDbConnection(connect);    con.Open();      Console.WriteLine("Made the connection to the Sales database");    OleDbCommand cmd = con.CreateCommand();        cmd.CommandText = "SELECT DISTINCT CustomerName "             + "FROM Customer, Item, Orders, OrderItem "             + "WHERE Customer.CustomerID = Orders.CustomerID "             + "AND Orders.OrderNumber = OrderItem.OrderNumber "             + "AND OrderItem.ItemNumber = Item.ItemNumber "             + "AND Description = 'computer'";    OleDbDataReader reader = cmd.ExecuteReader();    while(reader.Read())      Console.WriteLine(reader.GetString(0));    reader.Close();    con.Close();  } }