using System.Data;
using System.Data.SqlClient;
using System.Configuration;
 
var connectionStr = ConfigurationManager.ConnectionStrings["myconnection"].ConnectionString;
SqlCommand cmd = new SqlCommand();
cmd.Connection = new SqlConnection(connectionStr);
cmd.Connection.Open();
cmd.CommandText = "SELECT name, lastName FROM myTable";
var users = new DataSet();
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
adapter.Fill(users);
cmd.Connection.Close();
cmd.Connection.Dispose();