กด Enter หรือ Double Click แล้วให้ข้อมูลไปแสดงในฟอร์มหลัก VB.Net

public string ReturnValue1 {get;set;} 
public string ReturnValue2 {get;set;}
then set this inside your sub-form ok button click handler

private void btnOk_Click(object sender,EventArgs e)
{
    this.ReturnValue1 = "Something";
    this.ReturnValue2 = DateTime.Now.ToString(); //example
    this.Close();
}

using (var form = new frmImportContact())
{
    var result = form.ShowDialog();
    if (result == DialogResult.OK)
    {
        string val = form.ReturnValue1;            //values preserved after close
        string dateString = form.ReturnValue2;
        //Do something here with these values

        //for example
        this.txtSomething.Text = val;
    }
}

Public Property ReturnValue1() As String
	Get
		Return m_ReturnValue1
	End Get
	Set
		m_ReturnValue1 = Value
	End Set
End Property
Private m_ReturnValue1 As String
Public Property ReturnValue2() As String
	Get
		Return m_ReturnValue2
	End Get
	Set
		m_ReturnValue2 = Value
	End Set
End Property
Private m_ReturnValue2 As String


Private Sub btnOk_Click(sender As Object, e As EventArgs)
	Me.ReturnValue1 = "Something"
	Me.ReturnValue2 = DateTime.Now.ToString()
	'example
	Me.Close()
End Sub

Using form = New frmImportContact()
	Dim result = form.ShowDialog()
	If result = DialogResult.OK Then
		Dim val As String = form.ReturnValue1
		'values preserved after close
		Dim dateString As String = form.ReturnValue2
		'Do something here with these values

		'for example
		Me.txtSomething.Text = val
	End If
End Using

Module Module1
    Public connectionString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\DATA\PostCode.mdb;Persist Security Info=True;Jet OLEDB:Database Password=4410210091"
    Public Function GetTableForm(_SQL As String) As System.Data.DataTable
        Dim ds As New System.Data.DataSet()
        Dim conn1 As New System.Data.OleDb.OleDbConnection(connectionString)
        conn1.Open()
        Dim adapter1 As New System.Data.OleDb.OleDbDataAdapter(_SQL, conn1)
        adapter1.Fill(ds)
        Return ds.Tables(0)

    End Function
End Module

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
       
        Me.BindingSource1.DataSource = GetTableForm("SELECT * FROM Sett_Post_Province")
        ProvinceTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.BindingSource1, "Province", True))
        PvnIDTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.BindingSource1, "pvnID", True))
        SymbolTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.BindingSource1, "Symbol", True))
    End Sub
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim f As New Form2
        f.ShowDialog()
        If (f.PvItem <> 0) Then
            Me.BindingSource1.Filter = "PvnID = " & f.PvItem
        End If
    End Sub
End Class

Public Class Form2
    Public PvItem As Integer = 0
    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        DataGridView1.DataSource = GetTableForm("SELECT * FROM Sett_Post_Province").DefaultView

    End Sub
    Private Sub DataGridView1_CellDoubleClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellDoubleClick
        PvItem = Integer.Parse(DataGridView1(0, e.RowIndex).Value)
        Close()
    End Sub
End Class

Module Module1
    Public connectionString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\DATA\PostCode.mdb;Persist Security Info=True;Jet OLEDB:Database Password=4410210091"
    Public Function GetTableForm(_SQL As String) As System.Data.DataTable
        Dim ds As New System.Data.DataSet()
        Dim conn1 As New System.Data.OleDb.OleDbConnection(connectionString)
        conn1.Open()
        Dim adapter1 As New System.Data.OleDb.OleDbDataAdapter(_SQL, conn1)
        adapter1.Fill(ds)
        Return ds.Tables(0)

    End Function
End Module

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
       
        Me.BindingSource1.DataSource = GetTableForm("SELECT * FROM Sett_Post_Province")
        ProvinceTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.BindingSource1, "Province", True))
        PvnIDTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.BindingSource1, "pvnID", True))
        SymbolTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.BindingSource1, "Symbol", True))
    End Sub
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim f As New Form2
        f.ShowDialog()
        If (f.PvItem <> 0) Then
            Me.BindingSource1.Filter = "PvnID = " & f.PvItem
        End If
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Dim f As New Form2
        f.ShowDialog()
        For i As Integer = 0 To f.DataGridView1.RowCount - 1
            If Convert.ToBoolean(f.DataGridView1(0, i).Value) = True Then
                DataGridView1.Rows.Add(f.DataGridView1(1, i).Value, f.DataGridView1(2, i).Value, f.DataGridView1(3, i).Value)
            End If
        Next
    End Sub
End Class

Public Class Form2
    Public PvItem As Integer = 0
    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        DataGridView1.DataSource = GetTableForm("SELECT * FROM Sett_Post_Province").DefaultView

    End Sub
    Private Sub DataGridView1_CellDoubleClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellDoubleClick
        PvItem = Integer.Parse(DataGridView1(0, e.RowIndex).Value)
        Close()
    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        Close()
    End Sub
End Class