Type mismatch in criteria expression - vb.net

Question

I am new to visual basic . I want to delete a record based on phone number . The program will ask the user to enter his number and will delete the record after matching the phone number with the database . I tried doing so but it is giving me an error "Type mismatch in criteria expression".
I am using ms access 2007 and I have speciefied the data type of the phone column as Number . Here is my vb code . Please help me . It must be one of my silly mistakes . In the insert data module , I have specified the datatype as Long , before that I had specified it as Integer but the same error persists .
Imports System.Data.OleDb
Public Class Form5
Public Connstring As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source = C:\Users\AMEN\Documents\Railway.accdb"
Public Conn As New OleDbConnection
Private Sub Form5_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Conn.ConnectionString = Connstring
If Conn.State = ConnectionState.Closed Then
Conn.Open()
End If
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim okToDelete As MsgBoxResult = MsgBox("Are you sure you want to cancel your ticket?", MsgBoxStyle.YesNo)
If okToDelete = MsgBoxResult.Yes Then
Dim str As String
str = "Delete from Table2 Where Phone = '" & TextBox1.Text & "'"
Dim cmd As OleDbCommand = New OleDbCommand(str, Conn)
Try
cmd.ExecuteNonQuery()
cmd.Dispose()
Conn.Close()
MsgBox("Your Ticket Cancelled Sucessfully ! ")
Catch ex As Exception
MsgBox(ex.Message)
End Try
ElseIf okToDelete = MsgBoxResult.No Then
End If
End Sub
End Class

Answer 1

Phone numbers should be stored as strings not as numbers.
But a part from this your query is wrong if your Phone field is numeric.
In that case you don't need quotes around the TextBox1.Text. This will treat your input as a string and this string cannot be used to search in a numeric field.
The best approach is to use a parameterized query where you could specifiy the datatype of the parameter passed
(I have assumed that you have created the field Phone as Long Number in Access)
If okToDelete = MsgBoxResult.Yes Then
' Check if your user types really a number.
Dim number As Integer
if Not Int32.TryParse(TextBox1.Text, number) Then
MessageBox.Show("Not a valid number!")
return
End If
Dim str As String
str = "Delete from Table2 Where Phone = #phone"
Dim cmd As OleDbCommand = New OleDbCommand(str, Conn)
Try
cmd.Parameters.Add("#phone", OleDbType.Integer).Value = number
cmd.ExecuteNonQuery()
....