~~~

Dim objConn As New OleDb.OleDbConnection

Dim objDa As New OleDb.OleDbDataAdapter
Dim objComm As New OleDb.OleDbCommand
Dim objDs As New DataSet
Dim user, pass As String
user = userBox.Text
pass = passwordBox.Text

objConn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source='" & Application.StartupPath & "\stu.mdb'"
= "Select * from admin where administrator='" & user & " ' And password='" & pass & " '"

objComm.Connection = objConn
objDa.SelectCommand = objComm
objConn.Open()
objDa.Fill(objDs)

objComm.ExecuteNonQuery()
If objDs.Tables(0).Rows.Count= 0 Then
MsgBox("用户名或密码错！")
Else
Me.Hide()
mainform.Show()
End If