C# ado.net 操作(一)

简单的增删改查

 class Program
     {
         private static string constr = "server=.;database=northwnd;integrated security=sspi";
         static void Main(string[] args)
         {
             ExecuteXmlReader();
               ExecuteScalar();
             ExecuteReader();
             ExecuteNonQuery();
         }
         public static void ExecuteNonQuery()
         {
             string select = "update customers set contactname='bob' where contactname='Maria Anders'";
             SqlConnection con = new SqlConnection(constr);
             con.Open();
             SqlCommand cmd = new SqlCommand(select, con);
             int rows = cmd.ExecuteNonQuery();
             Console.WriteLine("{0} rows returned",rows);
             con.Close();
         }
         public static void ExecuteReader()
         {
             string select = "select contactname,companyname from customers";
             SqlConnection con = new SqlConnection(constr);
             con.Open();
             SqlCommand cmd = new SqlCommand(select, con);
             SqlDataReader reader = cmd.ExecuteReader();
             while (reader.Read())
             {
                 Console.WriteLine("Contact: {0,-24} Company: {1}",
                                    reader[], reader[]);
             }
         }
         static void ExecuteScalar()
         {
             string select = "SELECT COUNT(*) FROM Customers";
             SqlConnection conn = new SqlConnection(constr);
             conn.Open();
             SqlCommand cmd = new SqlCommand(select, conn);
             object o = cmd.ExecuteScalar();
             Console.WriteLine(o);
         }

         static void ExecuteXmlReader()
         {
             string select = "SELECT ContactName,CompanyName " +
                             "FROM Customers FOR XML AUTO";
             SqlConnection conn = new SqlConnection(constr);
             conn.Open();
             SqlCommand cmd = new SqlCommand(select, conn);
             XmlReader xr = cmd.ExecuteXmlReader();
             xr.Read();
             string data;
             do
             {
                 data = xr.ReadOuterXml();
                 if (!string.IsNullOrEmpty(data))
                     Console.WriteLine(data);
             } while (!string.IsNullOrEmpty(data));
             conn.Close();

         }

     }
 }