全局模块。 ADODB连接和SQL Server

Question

请帮助我。我在这里呆了好几个星期。我不知道如何解决它。

这里是我的连接代码：

Imports System.Text.RegularExpressions 

Module globalmodule 
Public conn As New ADODB.Connection 
Public rs As New ADODB.Recordset 
Public rss As New ADODB.Recordset 
Public trs As New ADODB.Recordset 
Public sql As String 

Public Function opendb() 
    If conn.State = 1 Then conn.Close() 
    conn.Open("Provider=SQLOLEDB.1;Data Source=ACER;Initial Catalog=dbEmployee;Integrated Security=True;") 
    Return 0 
End Function 

Function EmailAddressCheck(ByVal emailAddress As String) As Boolean 

    Dim pattern As String = "^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$" 
    Dim emailAddressMatch As Match = Regex.Match(emailAddress, pattern) 

    If emailAddressMatch.Success Then 
     EmailAddressCheck = True 
    Else 
     EmailAddressCheck = False 
    End If 

    If EmailAddressCheck = False Then 
     MsgBox("Entervalid E-mail ID") 
    End If 

End Function 


Public empid As String 

End Module 

表1这是关系到全球的模块形式。

下面的代码：

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
    opendb() 

End Sub 

Private Sub btnlogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnlogin.Click 

    If cmbutype.Text = "Employee" Then 
     sql = "select * from employee where empcode='" & txtuname.Text & "' and password='" & txtupass.Text & "'" 

     If rs.State = 1 Then 
      rs.Close() 

     rs.Open(sql, conn) 

     If rs.EOF = False Then 
      MDIMain.MasterToolStripMenuItem.Visible = False 
      MDIMain.EmployeeToolStripMenuItem.Visible = False 
      MDIMain.SearchToolStripMenuItem.Visible = False 
      MDIMain.LeaveToolStripMenuItem.Visible = False 
      MDIMain.EarnToolStripMenuItem.Visible = False 
      MDIMain.DeductionToolStripMenuItem.Visible = False 
      MDIMain.events.Visible = False 

      empid = txtuname.Text 


      ' MsgBox("login sucess") 
      MDIMain.Show() 

      Me.Hide() 
     End If 
    Else 
     sql = "select * from login where utypt='" & cmbutype.Text & "' and uname='" & txtuname.Text & "'" 

     If rs.State = 1 Then 
      rs.Close() 

     rs.Open(sql, conn) 

     If rs.EOF = False Then 
      sql = "select * from login where utypt='" & cmbutype.Text & "' and uname='" & txtuname.Text & "' and upass='" & txtupass.Text & "'" 

      If rs.State = 1 Then 
       rs.Close() 

      rs.Open(sql, conn) 

      If rs.EOF = False Then 
       ' MsgBox("login sucess") 
       MDIMain.Show() 
       Me.Hide() 
      Else 
       MsgBox("Incorrect password ") 
      End If 
     Else 
      MsgBox("login failed") 

     End If 

    End If 
End Sub 

我得到约adodb.connection错误是命名空间中的歧义“ADODB”和adodb.recordsets是命名空间中的暧昧“ADODB”

Answer 1

我会从此功能开始：

Public Function opendb() 
    If conn.State = 1 Then conn.Close() 
    conn.Open("Provider=SQLOLEDB.1;Data Source=ACER;Initial Catalog=dbEmployee;Integrated Security=True;") 
    Return 0 
End Function 

VB.Net不是VBScript/VB6。 VB.Net中的所有函数应具有返回类型。此外，Sql Server的最佳实践是不要一遍又一遍地重复使用相同的连接对象。这打破了驱动程序进行有效连接池的能力。所以你希望功能看起来更像这样：

'Using ADO.Net objects here because I'm more familiar, and the old ADO objects are really only for backwards compatibility with old code anyway 
Public Function opendb() As SqlConnection 
            'ADO.Net connection string may be slightly different 
    Dim result As New SqlConnection("Provider=SQLOLEDB.1;Data Source=ACER;Initial Catalog=dbEmployee;Integrated Security=True;") 
    result.Open() 
    Return result 
End Function 

现在让我们来看看登录代码。现在，我将留下一个巨大的安全问题，以纯文本形式存储密码（不要这么做！），而是专注于sql注入问题和基本连接。

Private Sub btnlogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnlogin.Click 
    Dim sql As String = "" 
    If cmbutype.Text = "Employee" Then 
     sql = "select * from employee where empcode= @Username AND password= @password" 
    Else 
     sql = "select * from login where utypt= @utype and uname= @username" 
    End If 

    Using cn As SqlConnection = opendb(), _ 
      cmd As New SqlCommand(sql, cn) 

     'Guessing at column types/lengths for all of these parameters 
     cmd.Parameters.Add("@username", SqlDbType.NVarChar, 50).Value = txtuname.Text 
     cmd.Parameters.Add("@password", SqlDbType.NVarChar, 64).Value = txtupass.Text  
     cmd.Parameters.Add("@utype", SqlDbType.VarChar, 15).Value = cmbutype.Text 

     cn.Open() 
     Dim rdr = cmd.ExecuteReader() 

     If Not rdr.Read() Then 
      MsgBox("Login Failed") 
      Exit Sub 
     End If 

     If cmbutype.Text <> "Employee" AndAlso rdr("upass").ToString() <> txtupass.Text Then 
      MsgBox("Password Incorrect") 
      Exit Sub 
     End If 
    End Using 

    ' MsgBox("login sucess") 

    If cmbutype.Text = "Employee" Then 
     MDIMain.MasterToolStripMenuItem.Visible = False 
     MDIMain.EmployeeToolStripMenuItem.Visible = False 
     MDIMain.SearchToolStripMenuItem.Visible = False 
     MDIMain.LeaveToolStripMenuItem.Visible = False 
     MDIMain.EarnToolStripMenuItem.Visible = False 
     MDIMain.DeductionToolStripMenuItem.Visible = False 
     MDIMain.events.Visible = False 

     empid = txtuname.Text 
    End If 

    MDIMain.Show() 
    Me.Hide()  
End Sub 

说明我是能够大大简化代码（嵌套少，并结合一些逻辑的），因为ADO.Net可以让你比SQL命令文本实际使用提供更多的查询参数。旧的ADODB不能这样做，因为它只使用位置参数。