get data to combobox vb.net

  Imports System.Data.OleDb
        Dim strSQL As New String
        Dim cmd As OledbCommand
        Dim Dr As OleDbDataReader
        connection.Open()
        strSQL = "select Myfield from MyTables"
        cmd = New OleDbCommand
        cmd.CommandText = strSQL
        cmd.Connection = connectionDB
        Dr = cmd.ExecuteReader
        While (Dr.Read())
            Combobox1.Items.Add(Dr("Myfield"))
        End While
        cmd.Dispose()
        Connection.Close()

clear all textbox vb.net

For Each ctl In Controls
            If TypeOf ctl Is TextBox Then ctl.Text = ""
        Next ctl

get data from database by listview

Dim strSQL As String
        Dim cmd As OleDbCommand
        Dim dtAdapter As OleDbDataAdapter
        Dim ds As DataSet
        Connection.Open()
        lvRecord.Items.Clear()
        strSQL = "select * from customer"
        cmd = New OleDbCommand(strSQL, connectionDB)
        dtAdapter = New OleDbDataAdapter(cmd)
        ds = New DataSet
        dtAdapter.Fill(ds, "customer")

        dt = ds.Tables("customer")
        Dim i As Integer
        For i = 0 To dt.Rows.Count - 1
            lvRecord.Items.Add(dt.Rows(i).ItemArray(1))
            lvRecord.Items(i).SubItems.Add(dt.Rows(i).ItemArray(2))
            lvRecord.Items(i).SubItems.Add(dt.Rows(i).ItemArray(3))
            lvRecord.Items(i).SubItems.Add(dt.Rows(i).ItemArray(5))
        Next
        Connection.Close()

My.Computer.Registry in visual basic.net

อ่านค่าจากรีจิสเตอร์

Dim readValue = My.Computer.Registry.GetValue(
    "HKEY_CURRENT_USER\Software\MyApp", "Name", Nothing)

สร้างค่ารีจิสเตอร์

My.Computer.Registry.SetValue("HKEY_CURRENT_USER\MyTestKey",
  "MyTestKeyValue", "This is a test value.") 

ลบค่ารีจิสเตอร์

My.Computer.Registry.CurrentUser.DeleteSubKey(
    "Software\TestApp")

อ่านและเขียนค่ารีจิสเตอร์

Dim regVersion = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(
                  "SOFTWARE\\Microsoft\\TestApp\\1.0", True)
If regVersion Is Nothing Then 
    ' Key doesn't exist; create it.
    regVersion = Microsoft.Win32.Registry.CurrentUser.CreateSubKey(
                 "SOFTWARE\\Microsoft\\TestApp\\1.0")
End If 

Dim intVersion As Integer = 0
If regVersion IsNot Nothing Then
    intVersion = regVersion.GetValue("Version", 0)
    intVersion = intVersion + 1
    regVersion.SetValue("Version", intVersion)
    regVersion.Close()
End If 

สนับสนุน

Platforms

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

 

อ้างอิง

 http://msdn.microsoft.com/en-us/library/85t3c3hf.aspx

ถ้ามี error ให้ข้ามไป visual basic .net

คำสั่ง On Error Resume Next
ถ้าพบ error ให้ข้ามบรรทัดคำสั่งไปเลย คือโปรแกรมจะไม่หยุดทำงานเมื่อมี error เกิดขึ้น
ตัวอย่าง

        Me.txtFileDir.Text = My.Computer.FileSystem.ReadAllText(Application.StartupPath & "\Config.ini")

เปิดโปรแกรมแล้วไม่พบไฟล์ Config.ini โปรแกรมจะ error ทันทีและปิดตัวเองลง
รูปแบบการใช้งาน
Private Sub on_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        On Error Resume Next
        Me.txtFileDir.Text = My.Computer.FileSystem.ReadAllText(Application.StartupPath & "\Config.ini")
    End Sub

Browser file from directory in visual basic .net

1.Create Windows From App
2.Add TextBox And Button Double Click Button Insert Code

3.Insert namespace
Imports System.IO
Imports System.Data
Imports System.Windows.Forms

Dim FolderBrowser As New FolderBrowserDialog
        If FolderBrowser.ShowDialog = DialogResult.OK Then
            txtFileDir.Text = FolderBrowser.SelectedPath
            Dim root As Environment.SpecialFolder = Environment.SpecialFolder.MyComputer
        End If