How to retrieve an autonumber value form MS Access datatable and convert it to int64

Question

I want to retrieve an auto number value from the MS Access data table from column name "id" and convert it to Int64 in C# in asp.net. How can I do it

Answer 1

We probably need more context here.

However:

Say we have this markup:

      <asp:GridView ID="GridView1" runat="server" DataKeyNames="ID" CssClass="table" >
            <Columns>
                <asp:TemplateField HeaderText="Get ID" ItemStyle-HorizontalAlign="Center" >
                    <ItemTemplate>
                        <asp:Button ID="cmdGetID" runat="server" Text="Show ID" OnClick="cmdGetID_Click" />
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>

And then this code to fill the grid.

   protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
            LoadGrid(); 
    }

    void LoadGrid()
    {
        using (OleDbCommand cmdSQL = 
            new OleDbCommand("SELECT ID, FirstName, LastName, HotelName, City FROM tblHotels ORDER BY HotelName",
            new OleDbConnection(Properties.Settings.Default.AccessDB)))
        {
            cmdSQL.Connection.Open();
            GridView1.DataSource = cmdSQL.ExecuteReader();
            GridView1.DataBind();
        }
    }

Ok, we now have this:

Ok, so now the button code when we click on a row - lets get that ID from Access.

   protected void cmdGetID_Click(object sender, EventArgs e)
    {
        Button cmdSel = (Button)sender;
        GridViewRow gvRow = (GridViewRow)cmdSel.Parent.Parent;

        int MyID32 = Convert.ToInt32(gvRow.Cells[1].Text);
        Int64 MyID64 =  Convert.ToInt64(gvRow.Cells[1].Text);

        Debug.WriteLine("ID as Int 32 = " + MyID32);
        Debug.WriteLine("ID as Int 64 = " + MyID64);

        Int64 MyID64Fromtable = 0;

        DataTable rstData = new DataTable();
        using (OleDbCommand cmdSQL = new OleDbCommand("SELECT * FROM tblHotels where ID = @ID",
                                     new OleDbConnection(Properties.Settings.Default.AccessDB)))
        {
            cmdSQL.Connection.Open();
            cmdSQL.Parameters.Add("@ID", OleDbType.Integer).Value = MyID32;
            rstData.Load(cmdSQL.ExecuteReader());

            MyID64Fromtable = Convert.ToInt64(rstData.Rows[0]["ID"]);


        }
        // at this point, we have a 64 bit var called MyID64FromTable
        Debug.Print("64 ID value direct from table = " + MyID64Fromtable.ToString());
    }

Output:

ID as Int 32 = 307
ID as Int 64 = 307
64 ID value direct from table = 307

So that button code pulls the int32 value from Access (from the grid).

We also for fun, created a data table.

Filled it with a Access query, and then pulled that int32 "ID" value (the autonumber) from the table into a variable.

So, the one line of really pulling from a data table?

this line is most like what you are looking for:

Int64 MyID64Fromtable = 0;
MyID64Fromtable = Convert.ToInt64(rstData.Rows[0]["ID"]);