چگونه به Data Base SQL Server 2005 متصل شویم

using System.Data.SqlClient;O
SqlConnection sqlconnection = new SqlConnection();O
            try
           }
                sqlconnection.ConnectionString = "";O
                sqlconnection.Open();O
                SqlCommand sqlcommand = new SqlCommand();O
                sqlcommand.Connection = sqlconnection;O
                sqlcommand.CommandType = CommandType.Text;O
                sqlcommand.CommandText = "Select Studnumber From Student";O
                string data = sqlcommand.ExecuteScalar().ToString();O
                sqlcommand.ExecuteNonQuery();O
        {
            catch
          }
            {

finally
            }
                sqlconnection.Close();O
           {