1 class Program
 2     {
 3         private static string constr = "server=.;database=northwnd;integrated security=sspi";
 4         static void Main(string[] args)
 5         {
 6             ExecuteXmlReader();
 7               ExecuteScalar();
 8             ExecuteReader();
 9             ExecuteNonQuery();
10         }
11         public static void ExecuteNonQuery()
12         {
13             string select = "update customers set contactname='bob' where contactname='Maria Anders'";
14             SqlConnection con = new SqlConnection(constr);
15             con.Open();
16             SqlCommand cmd = new SqlCommand(select, con);
17             int rows = cmd.ExecuteNonQuery();
18             Console.WriteLine("{0} rows returned",rows);
19             con.Close(); 
20         }
21         public static void ExecuteReader()
22         {
23             string select = "select contactname,companyname from customers";
24             SqlConnection con = new SqlConnection(constr);
25             con.Open();
26             SqlCommand cmd = new SqlCommand(select, con);
27             SqlDataReader reader = cmd.ExecuteReader();
28             while (reader.Read())
29             {
30                 Console.WriteLine("Contact: {0,-24} Company: {1}",
31                                    reader[0], reader[1]);
32             }
33         }
34         static void ExecuteScalar()
35         {
36             string select = "SELECT COUNT(*) FROM Customers";
37             SqlConnection conn = new SqlConnection(constr);
38             conn.Open();
39             SqlCommand cmd = new SqlCommand(select, conn);
40             object o = cmd.ExecuteScalar();
41             Console.WriteLine(o);
42         }
43 
44         static void ExecuteXmlReader()
45         {
46             string select = "SELECT ContactName,CompanyName " +
47                             "FROM Customers FOR XML AUTO";
48             SqlConnection conn = new SqlConnection(constr);
49             conn.Open();
50             SqlCommand cmd = new SqlCommand(select, conn);
51             XmlReader xr = cmd.ExecuteXmlReader();
52             xr.Read();
53             string data;
54             do
55             {
56                 data = xr.ReadOuterXml();
57                 if (!string.IsNullOrEmpty(data))
58                     Console.WriteLine(data);
59             } while (!string.IsNullOrEmpty(data));
60             conn.Close();
61 
62         }
63 
64     }
65 }