如何存储 sqlDataReader 的值？并进行比较？
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();
正如您在这里所看到的，我想将 SQL 中的 flight_seat 列存储到 availableSeat 中，以检查是否有可用座位。
我怎样才能做到这一点？因为它不断地去往其他地方。
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();
As you can see here, I would like to store flight_seat column from SQL into availableSeat in order to check whether there is a seat available.
How can I do that? because it keeps going to else.
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availableSeat.Equals()是比较而不是赋值。您需要分配该值。例如availableSeat.Equals()is a comparison not an assignment. You would need to assign the value. For example将其更改为：
Equals()方法用于比较目的（相等）而不是赋值。此外，在 C# 中，通过将=左侧的变量设置为右侧语句的结果来完成赋值。您需要将
reader中的值转换为int，因为它存储为object。您还应该检查null值，因为它来自数据库：Change it to:
The
Equals()method is used for comparison purposes (equality) and not assignment. Furthermore, assignments are done in C# by setting the variable on the left of the=to the result of the statement on the right.You need to cast the value in the
readerto anintbecause it is stored as anobject. You should also check for anullvalue since this is coming from a database: