how to link dropdown menu to other class - sql

Question

i have a problem where i have to link dropdown menu to other class, which the class is sqlcommand
so my code a bit much like this
Form1.vb
Public Class Input
Dim CallSQL As New SQL Private Sub Button1_Click(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles Button1.Click
ListBox1.Visible = True
If ListBox1.SelectedValue = "A" Then
-------"I DONT KNOW HOW TO COMMAND HERE "--
End If
If ListBox1.SelectedValue = "B" Then
-------"I DONT KNOW HOW TO COMMAND HERE "---------
End If
End Sub
End Class
and i need to match the dropdown from here
SQL.vb
Public Class SQL
Private Sub GetRoadDataFromDatabase(station)
ExecuteSqlCommand("exec '" & station & "', 'A'", "TableA")
End Sub
Public Sub GettrainDataFromDatabase(station)
ExecuteSqlCommand("exec '" & station & "', 'B'", "TableB")
End Sub
so when user choose A, executesql data for road, and when choose B execute data for train. please help me.this suppose to be a simple task. but since im new in vb.bet i cant figure it out

Answer 1

You want to execute GetRoadDataFromDatabase if user selects option 'A' and GetTrainDataFromDatabase if user selects B. Simply create instance of SQL class outside of IF/ELSE statements and call relevant method in IF/ELSE:
Public Class Input
Dim CallSQL As New SQL Private Sub Button1_Click(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles Button1.Click
ListBox1.Visible = True
Dim sql AS SQL =new SQL() 'Please check this if it is valid VB.Net statement
If ListBox1.SelectedValue = "A" Then
'Supposing you have got station already
sql.GetRoadDataFromDatabase(station)
End If
If ListBox1.SelectedValue = "B" Then
'Supposing you have got station already
sql.GettrainDataFromDatabase(station)
End If
End Sub
End Class
EDIT:- Not making methods public
As you have stated that you don't want to make the two functions public, an option is to write a gateway function to accept parameters and then call the desired private method.
Public Class SQL
Private Sub GetRoadDataFromDatabase(station)
ExecuteSqlCommand("exec '" & station & "', 'A'", "TableA")
End Sub
'THOUGH YOUR THIS FUNCTION IS PUBLIC IN QUESTION
Private Sub GettrainDataFromDatabase(station)
ExecuteSqlCommand("exec '" & station & "', 'B'", "TableB")
End Sub
Public Sub CallDBFunction(station as string, code as string)
If code == "A" Then
GetRoadDataFromDatabase(station)
Else
GetTrainDataFromDatabse(station)
End If
End Sub
End Class