[vbnet]

frmNew.vb

كود :

Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
    If txtName.Text = Nothing Then
        MsgBox("يجب إدخال الاسم", MsgBoxStyle.Critical, "عذراً")
        txtName.Focus()
    Else

        If ExistName(txtName.Text) Then '<<<<<<<<<<<<<<<<<<<<<<<<<
            MsgBox("الاسم موجود مسبقاً", MsgBoxStyle.Critical, "عذراً") '<<<<<<<<<<<<<<<<<<<<<<<<<
            Exit Sub                        '<<<<<<<<<<<<<<<<<<<<<<<<<
        Else
            SaveData()                      '<<<<<<<<<<<<<<<<<<<<<<<<<
        End If

        MsgBox("تم تخزين البيانات بنجاح", MsgBoxStyle.Information, "ألف مبروك")
        txtName.Text = Nothing
        txtName.Focus()
    End If
End Sub

Private Function ExistName(ByVal theName As String) As Boolean '<<<<<<<<<<<<<<<<<<<<<<<<<<
    Dim ExistDataSQl As String = "SELECT [TheName] FROM [TheTable] WHERE [TheName]=@TheName"
    Dim ExistDataCMD As New OleDbCommand(ExistDataSQl, Con)
    ExistDataCMD.Parameters.AddWithValue("@TheName", theName)
    Dim ExistDataADP As New OleDbDataAdapter(ExistDataCMD)
    If ExistDataADP.Fill(New DataTable) > 0 Then Return True
End Function