คอมโบบ๊อก ใน visual 2008 มึนตื๊บมาหลายวันแล้วคับ ช่วยหน่อยคับ

Imports System.Data
Imports System.Data.OleDb
Public Class Form2


    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
     
        If example.Text = "ID Code" Then
            sql = "select * from factory1 where ID_Code Like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Plt Bld Id" Then
            sql = "select * from factory1 where Plt_Bld_Id Like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Tsic Id" Then
            sql = "Select * from factory1 where Tsic_Id like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Id No" Then
            sql = "Select * from factory1 where Id_No like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Number Factory" Then
            sql = "Select * from factory1 where Number_Factory like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Type code factory" Then
            sql = "Select * from factory1 where Type_code_factory like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Industry" Then
            sql = "Select * from factory1 where Industry like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Corporate Name" Then
            sql = "Select * from factory1 where Corporate_Name like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Factory_Building" Then
            sql = "Select * from factory1 where Factory_Building like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Trader" Then
            sql = "Select * from factory1 where Trader like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Name Contract" Then
            sql = "Select * from factory1 where Name_Contract like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Date control" Then
            sql = "Select * from factory1 where Date_control like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Acc responsible" Then
            sql = "Select * from factory1 where Acc_responsible like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Address" Then
            sql = "Select * from factory1 where Address like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Address Estate" Then
            sql = "Select * from factory1 where Address_Estate like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Group" Then
            sql = "Select * from factory1 where Group like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Road" Then
            sql = "Select * from factory1 where Road like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "District" Then
            sql = "Select * from factory1 where District like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Zone" Then
            sql = "Select * from factory1 where Zone like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Province" Then
            sql = "Select * from factory1 where Province like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Post Code" Then
            sql = "Select * from factory1 where Post_Code like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Number" Then
            sql = "Select * from factory1 where Number like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "NumberFax" Then
            sql = "Select * from factory1 where NumberFax like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Expr1014" Then
            sql = "Select * from factory1 where Expr1014 like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Transformer size (kVA) SUM" Then
            sql = "Select * from factory1 where Transformer_size like '" & TextBox1.Text & "%'"
        ElseIf example.Text = "Size kW approval SUM" Then
            sql = "Select * from factory1 where Size_kW_approval like '" & TextBox1.Text & "%'"
        End If
        dt.Clear()
        da = New OleDbDataAdapter(sql, Conn)
        da.Fill(dt)
        dtg.DataSource = dt
    End Sub
    Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        sql = "Select * from factory1"
        da = New OleDbDataAdapter(sql, Conn)
        da.Fill(dt)
        dtg.DataSource = dt

        Dim _DR As DataRow
        Dim _DT As New DataTable



        _DT.Columns.Add("Data")
        _DT.Columns.Add("SQLString")
        _DR = _DT.NewRow
        _DR("Data") = "น้อยกว่า 1175"
        _DR("SQLString") = "Transformer_size < 1175"



        _DR("Data") = "1175 ถึง 3529"
        _DR("SQLString") = "Transformer_size >= 1175 And Transformer_size <= 3529"
        _DT.Rows.Add(_DR)



        _DR = _DT.NewRow
        _DR("Data") = "มากกว่า 3529"
        _DR("SQLString") = "Transformer_size > 3529"
        _DT.Rows.Add(_DR)



        c2.DataSource = _DT
        c2.DisplayMember = "Data"
        c2.ValueMember = "SQLString"
    End Sub

    Private Sub example_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles example.SelectedIndexChanged
        Try

            Me.Text = c2.SelectedValue
        Catch ex As Exception
            c2.Text = Nothing

        End Try
    End Sub

    Private Sub c2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles c2.SelectedIndexChanged
        
    End Sub
End Class