VB.net Getting Scalar to save a value to a variable

Question

I've been looking through the forums with no luck. I am trying to retrieve a value from a database and store it to a variable. The closest I got was following This. Here is my Code:

Dim dblAircraftHourlyRate As Double
    Dim intAircraftID As Integer
    intAircraftID = ddAircraft.SelectedItem.Value
    Dim mySqlComm As String = "SELECT HourlyRate FROM Aircraft WHERE AircraftID = '" & intAircraftID & "'"
    Using cn As New SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\Rollin Laptop\Desktop\CurrentAll2Fly3\App_Data\ASPNETDB.MDF;Integrated Security=True;User Instance=True"), _
        cmd As New SqlCommand(mySqlComm, cn)
        cn.Open()
        dblAircraftHourlyRate = Convert.ToDouble(cmd.ExecuteScalar())
    End Using

I'm not sure why, but instead of saving the HourlyRate to the dblAircraftHourlyRate, it is saving the intAircraftID to dblAircraftHourlyRate. I'm also not sure why the example code did not close the database connection. Any ideas on how to fix this to get the correct variable?

Answer 1

My solution had nothing to do with the question, but I had a separate bit of code that was executing after the bit I posted. It was resetting the value of dblAircraftHourlyRate such that dblAircraftHourlyRate = ddAircraft.SelectedItem.Value After I commented out the line, the code worked perfectly. To clarify, the value in the dropdownlist was the AircraftID, not the HourlyRate.

Tim Schmelter also helped me out in his explanation of how Connection-Pooling works:

Connection-Pooling is enabled by default. Default means that it's enabled even if you don't specify the Pooling parameter in your connection-string. Connection-pooling helps to improve performance since it maintains the state of the physical connections. So even if you close a connection the physical connection keeps open (If you check it in the database). You are using the Using-statement which is best practise. Disposing a connection will "close" it. – Tim Schmelter