C# - Connecting to an Access MDB file using WPF (The ConnectionString Property has not been initialized)
<p>Let me start by saying I've only been coding C# for about 3-4 month. </p>

<p>I am trying to get a basic understanding of how databases are accessed within Visual studio so that I can both insert, update and delete data. I have tried various different tests and I think I've come to the conclusion that there's something about WPF's that OleDb doesn't quite like. I have created 2 identical projects, one using Windows Forms and another using WPF. The Windows Forms version of the project works absolutely fine however the WPF project does not, giving me the error </p>

<p>"The ConnectionString Property has not been initialized"</p>

<p>I have no idea how to fix this. I've been scouring the internet for the best part of 12 hours and still had absolutely no success.</p>

<p>Here is the original code for the WPF file. It is the same as the Windows Form code</p>

<pre><code>public partial class MainWindow : Window
{

    OleDbCommand cmd = new OleDbCommand();
    OleDbConnection cn = new OleDbConnection();
    OleDbDataReader dr;

    public MainWindow()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {

        cn.ConnectionString = @"Provider = Microsoft.Jet.OLEDB.4.0; Data Source = C:\Users\MarkB\Documents\testing.mdb";
        cmd.Connection = cn;
        loaddata();
    }
    private void loaddata()
    {
        listBox1.Items.Clear();
        listBox2.Items.Clear();
        listBox3.Items.Clear();
        listBox4.Items.Clear();
        try
        {
            string q = "select * from info";
            cmd.CommandText = q;
            cn.Open();
            dr = cmd.ExecuteReader();
            if(dr.HasRows)
            {
                while(dr.Read())
                {
                    listBox1.Items.Add(dr[0].ToString());
                    listBox2.Items.Add(dr[1].ToString());
                    listBox3.Items.Add(dr[2].ToString());
                    listBox4.Items.Add(dr[3].ToString());
                }
            }
            dr.Close();
            cn.Close();
        }
        catch(Exception e)
        {
            cn.Close();
            MessageBox.Show(e.Message.ToString());
        }
    }

    private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
    {
        ListBox l = sender as ListBox;
        if(l.SelectedIndex != -1)
        {
            listBox1.SelectedIndex = l.SelectedIndex;
            listBox2.SelectedIndex = l.SelectedIndex;
            listBox3.SelectedIndex = l.SelectedIndex;
            listBox4.SelectedIndex = l.SelectedIndex;
        }

    }

    private void button1_Click(object sender, EventArgs e)
    {

        if ((textBox1.Text!="") &amp;&amp; (textBox2.Text!=""))
        {
            string q ="insert into info (firstname,surname,address) values ('" + textBox1.Text + "','" + textBox2.Text + "','" + textBox3.Text +"')";
            dosomething(q);
            textBox1.Text = null;
            textBox2.Text = null;
            textBox3.Text = null;
        }
    }

    private void dosomething(String q)
    {
        try
        {
            cn.Open();
            cmd.CommandText = q;
            cmd.ExecuteNonQuery();
            MessageBox.Show("Data Saved");
            cn.Close();
            loaddata();
        }
        catch (Exception e)
        {
            cn.Close();
            MessageBox.Show(e.Message.ToString());
        }
    }

    private void button2_Click(object sender, EventArgs e)
    {
        if(listBox1.SelectedIndex !=-1)
            {
            string q = "delete from info where id =" + listBox1.SelectedItem.ToString();
            dosomething(q);
        }
    }
}
</code></pre>

<p>If anyone can help it would be greatly appreciated. I know the problem must stem from the connection aspect of the code</p>