验证用户名和密码

1、

Dim conn As New ADODB.Connection
Dim rs As New ADODB.Recordset
conn.connectionstring="Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=StoreHouseMaster;Data Source=IBM"

conn.open
rs.open "select * from operator where user_name='" & username.text & "' and userpassword='" & userpassword.text & "'",conn

if rs.eof then
    msgbox "密码错误！"
else
    msgbox "密码正确！"
end if

2、

上面的代码有安全性问题啊
可以在username里面输入字串“1 or 1=1 --”就可以跳过密码检测

rs.open "select userpassword from operator where user_name='" & username.text & "'"
if rs(0)=userpassword.text  then
    msgbox "密码错误！"
else
    msgbox "密码正确！"
end if

还要考虑用户不合法的情况：

rs.open "select userpassword from operator where user_name='" & username.text & "'"
if rs.recordcount=0 then
    msgbox "用户不存在!"
elseif rs(0)<>userpassword.text  then
    msgbox "密码错误！"
else
    msgbox "密码正确！"
end if

3。

Private Sub Command1_Click() '登陆
    On Error GoTo Err
    If UserName.Text = "" Then
        MsgBox "请输入操作员！", vbInformation, "提示"
        Exit Sub
    End If
    Dim conn As New ADODB.Connection
    Dim rs As New ADODB.Recordset
    conn.ConnectionString = "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=StoreHouseMaster;Data Source=IBM"
    cn.Open
    rs.CursorLocation = adUseClient

    Dim name As String, passa As String
    name = Trim(UserName.Text)
    passa = Trim(userpassword.Text)

    rs.Open "select * from Operator where  user_name='" & name & "'", cn, adOpenKeyset, adLockReadOnly
   
    If rs.EOF Then
        MsgBox "该用户尚未注册！", vbOKCancel, "提示"
        UserName.SetFocus
        UserName.SelStart = 0
        UserName.SelLength = Len(UserName.Text)
        Exit Sub
    Else
        If passa <> Trim(rs!userpassword) Then
        MsgBox "密码不正确，请重输！！！", vbQuestion, "提示"
        userpassword.Text = ""
        userpassword.SetFocus
        Exit Sub
    End If
    Me.Hide
    main.Show        'main为主窗口名称
    Exit Sub
Err:
    MsgBox Err.Description
End Sub