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[0], reader[1]);
            }
        }
        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();

        }

    }
}