//实现了IDisposable接口的类，用using括起来

//插入数据

string connString = "Data Source=(local);Initial Catalog=Linq;Integrated Security=SSPI";

using (SqlConnection conn = new SqlConnection(connString))

{

    conn.Open();

    using (SqlCommand cmd = conn.CreateCommand())

    {

        cmd.CommandText = "insert into orders (Amt,Country,City) values(240,'中国','绍兴');";

        cmd.ExecuteNonQuery();

        Console.WriteLine("插入成功");

        Console.ReadKey();

    }

}

//用SqlDataReader方式读取数据

string connString = "Data Source=(local);Initial Catalog=Linq;Integrated Security=SSPI";//用windows用户登录

using (SqlConnection conn = new SqlConnection(connString))

{

    conn.Open();

    using (SqlCommand cmd = conn.CreateCommand())

    {

        cmd.CommandText = "select * from orders";

        using (SqlDataReader reader = cmd.ExecuteReader())

        {

            while (reader.Read())

            {

                string city = reader.GetString(reader.GetOrdinal("city"));

                decimal amt = reader.GetDecimal(reader.GetOrdinal("amt"));

                Console.WriteLine(string.Format("城市：{0}, 金额：{1}", city, amt));

            }

        }

        Console.ReadKey();

    }

}

//用DataSet的方式来连接数据库

string connString = "Data Source=(local);Initial Catalog=Linq;Integrated Security=SSPI";//用windows用户登录

using (SqlConnection conn = new SqlConnection(connString))

{

    conn.Open();

    using (SqlCommand cmd = conn.CreateCommand())

    {

        cmd.CommandText = "select * from orders";

        DataSet dataset = new DataSet();

        SqlDataAdapter adapter = new SqlDataAdapter(cmd);

        /*把查询出来的结果填充到dataset中，并指定一个表面：orders

         *注意：

         *      如果不指定表名，直接用adapter.Fill(dataset)得方式填充，DataTable接收的时候根据索引号

         *      DataTable table = dataset.Tables[0];

         */

        adapter.Fill(dataset,"orders");

        DataTable table = dataset.Tables["orders"];

        for (int i = ; i < table.Rows.Count; i++)

        {

            DataRow row = table.Rows[i];

            string city = Convert.ToString(row["city"]);

            Console.WriteLine(city);

        }

        Console.ReadKey();

    }

}