string queryString ="select count(*) as stuNum from student";
string connectionString = "server='(local)';database='mytable';uid='sa';pwd='sa'"; 
　　using (SqlConnection connection = new SqlConnection( connectionString))
　　{
　　SqlCommand command = new SqlCommand( queryString, connection); 
      connection.Open();
　　SqlDataReader reader = command.ExecuteReader();
　　try
　　{
　　while (reader.Read())
　　{
     int zh = 0;
    zh = Convert.ToInt32(reader["stuNum"]); //强制数据转换
　　}
　　}
　　finally
　　{
　　// Always call Close when done reading.
　　reader.Close();
　　}