ผมเขียนโค้ดแบบนี้ครับเวลาตอนค้นหาไม่แสดงข้อมูลที่ต้องการ โดยหลังจากทำการโหลดข้อมูลมาแสดงในตาราง หลังจากการกดปุ่มค้นหาข้อมูลในตารางก็จะหายไปหมดครับ ตอนนี้ติดตรงนี้มานานแล้วเป็นมือใหม่ไม่ได้จบทางด้านคอมมาแต่สนใจงานด้านนี้ครับ วานผู้รู้ช่วยหน่อยครับ ขอบคุณครับ

Imports System.Data
Imports System.Data.OleDb
Public Class Form1
    Public connstring As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\Chainarong.k\Desktop\Database app\PrimerDatabase2015New.mdb;persist security info = false"
    Public con As New OleDbConnection
    Dim com As OleDbCommand
    Dim oledbda As OleDbDataAdapter
    Dim ds As DataSet
    Dim dt As DataTable
    Dim str As String
    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click

            Try

                str = "select * from tbl_primerbank where Agent ='" & TextBox1.Text & "'"
                com = New OleDbCommand(str, con)
                oledbda = New OleDbDataAdapter(com)
                ds = New DataSet
                oledbda.Fill(ds, "tbl_primerbank")
            con.Close()
            DataGridView1.DataSource = ds
            DataGridView1.DataMember = "tbl_primerbank"
            Catch ex As Exception
                MsgBox(ex.Message)
            End Try

        TextBox1.Clear()
        DataGridView1.Visible = True
    End Sub

    Private Sub DataGridView1_CellContentClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick

    End Sub
    Private Sub showdata()

        Dim oledbc As New OleDbCommand
        Dim oledbdr As OleDbDataReader
        Dim c As Integer
        c = 0
        With oledbc
            .Connection = con
            .CommandText = "select*from tbl_primerbank"
        End With
        oledbdr = oledbc.ExecuteReader
        DataGridView1.Rows.Clear()
        If oledbdr.HasRows Then
            While oledbdr.Read
                DataGridView1.Rows.Add()
                DataGridView1.Item(0, c).Value = oledbdr.Item(0)
                DataGridView1.Item(1, c).Value = oledbdr.Item(1)
                DataGridView1.Item(2, c).Value = oledbdr.Item(2)
                DataGridView1.Item(3, c).Value = oledbdr.Item(3)
                DataGridView1.Item(4, c).Value = oledbdr.Item(4)
                DataGridView1.Item(5, c).Value = oledbdr.Item(5)
                DataGridView1.Item(6, c).Value = oledbdr.Item(6)
                DataGridView1.Item(7, c).Value = oledbdr.Item(7)
                DataGridView1.Item(8, c).Value = oledbdr.Item(8)
                DataGridView1.Item(9, c).Value = oledbdr.Item(9)
                DataGridView1.Item(10, c).Value = oledbdr.Item(10)
                DataGridView1.Item(11, c).Value = oledbdr.Item(11)
                DataGridView1.Item(12, c).Value = oledbdr.Item(12)
                DataGridView1.Item(13, c).Value = oledbdr.Item(13)
                DataGridView1.Item(14, c).Value = oledbdr.Item(14)
                DataGridView1.Item(15, c).Value = oledbdr.Item(15)
                DataGridView1.Item(16, c).Value = oledbdr.Item(16)
                DataGridView1.Item(17, c).Value = oledbdr.Item(17)
                DataGridView1.Item(18, c).Value = oledbdr.Item(18)
                DataGridView1.Item(19, c).Value = oledbdr.Item(19)
                DataGridView1.Item(20, c).Value = oledbdr.Item(20)
                DataGridView1.Item(21, c).Value = oledbdr.Item(21)
                DataGridView1.Item(22, c).Value = oledbdr.Item(22)
                DataGridView1.Item(23, c).Value = oledbdr.Item(23)
                DataGridView1.Item(24, c).Value = oledbdr.Item(24)
                DataGridView1.Item(25, c).Value = oledbdr.Item(25)
                DataGridView1.Item(26, c).Value = oledbdr.Item(26)
                DataGridView1.Item(27, c).Value = oledbdr.Item(27)

                c = c + 1
            End While
        End If


    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If con.State = ConnectionState.Closed Then
            con.ConnectionString = connstring
            con.Open()
        End If
        Call showdata()


    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Call showdata()

    End Sub
End Class