Question

tl;dr Method of copying contents of an SQL query to an array or a string or a listbox. Single columns, multiple rows.

Working on a small project for some extra course credit.
Developing it currently in Visual Studio 2010.
Essentially is an interactive menu where users select items and can add them to an inbuilt
list and it will calculate total nutritional information and costs etc..

I’m having an issue however. When the user reaches the order builder page they can select the type of item they wish to buy.

E.G.

Beef

Clicking this should then populate a list box with all the related items.

I’m hoping to do this via a database connection.
I currently have an embedded database.

Their where 2 ways I’ve tried to do this but both proved unsuccessful or perhaps I’m just doing it wrong.

First method.

 Dim index As Integer = 0
    Dim length As Integer = adapter.productscounter()
    ' Small query that works out total number of rows.

    For index = 0 To length
        ListBox1.Items.Add(adapter.SelectBeef(index))


    Next

This gives me the error:

There is no row at position 0.

which I seem unable to solve. The query runs upon trial execution and theirs something their.

Index out of range exception

The other method I was attempting was similar code however using an array and then copying the contents of that into the listbox.

    Dim index As Integer
    Dim test(5)
    Dim length As Integer = adapter.productscounter()
    Dim counter As Integer


    For index = 0 To length

        test(index) = adapter.SelectChicken()
        counter = counter + 1

    Next


    For counter = 0 To length
        ListBox1.Items.Add(test(index))

    Next

Generates:

Argument nullexception 

Value cannot be null.
Parameter name: item.

Answer 1

In Visual Basic, the standard is to start a list with element 1, not element 0. You could try:

For index = 1 To length
    ListBox1.Items.Add(adapter.SelectBeef(index))
Next

Though of course, I have no insight in what the SelectBeef method does.