Question

int availableSeat = 0;
string query = "select flight_no flight_seat from flight_info where flight_departure_time = @selectedFlight AND flight_from = @flightFrom AND flight_to = @flightTo ";
string url = "Server=localhost;Database=flight;uid=******;password=*****";
con1 = new MySqlConnection(url);
con1.Open();
cmd1 = new MySqlCommand(query,con1);
cmd1.Parameters.AddWithValue("@selectedFlight",comboBox3.SelectedItem);
cmd1.Parameters.AddWithValue("@flightFrom",comboBox1.SelectedItem);
cmd1.Parameters.AddWithValue("@flightTo",comboBox2.SelectedItem);
reader = cmd1.ExecuteReader();
while (reader.Read()) 
{
    availableSeat.Equals(reader["flight_seat"]);
    if(availableSeat > 0)
    {
        MessageBox.Show("The seat is available!!");
    }
    else
    {
        MessageBox.Show("Sorry, all seat has been booked!!");
    }
}
con1.Close();

正如您在此处所见，我想将SQL中的flight_seat列存储到availableSeat，以检查是否有可用的座位。

我该怎么做？因为它不断前进。

Answer 1

将其更改为：

availableSeat = (int)reader["flight_seat"]);

Equals()方法用于比较目的（相等）而不是赋值。此外，通过将=左侧的变量设置为右侧语句的结果，可以在C＃中完成赋值。

您需要将reader中的值转换为int，因为它存储为object。您还应检查null值，因为它来自数据库：

availableSeat = reader["flight_seat"].Equals(DBNull.Value)
                    ? 0
                    : (int)reader["flight_seat"];

Answer 2

availableSeat.Equals()是比较而不是作业。您需要分配值。例如

availableSeat = (int)reader["flight_seat"];

如何从sqlDataReader存储值？和比较？

2 个答案: