VB6运行时错误3709连接不能用于执行操作 - 它关闭或无效 [英] VB6 run-time error 3709 the connection cannot be used to perform the operation-it is either closed or invalid

问题描述

每次运行程序时，我总是会收到此错误。

  Dim  rs  As  新 ADODB.Recordset 
 rs.Open  选择*来自tbluser其中uname ='& txtuser.Text&  '，cnn，adOpenStatic，adLockReadOnly 
 如果 rs.RecordCount<  1  然后 
 MsgBox  无效的用户名！，vbCritical， 登录错误 
 txtuser.SetFocus 
 退出  Sub  
 否则 
 如果 txtpass.Text = rs！pword 那么 
卸载我 
加载Form2 
 Form2.Show 
 退出  Sub  
 否则 
 MsgBox  密码无效！，vbCritical， 登录错误 
 txtpass.SetFocus 
 退出  Sub  
 结束 如果 
 结束 如果 
 设置 rs =  Nothing  

模块代码：

 选项 明确 
 
 公开 cnn 作为 ADODB.Connection 
 公共  Sub  getconnected（）
 设置 cnn = 新 ADODB.Connection 
 cnn。 CursorLocation = adUseClient 
 cnn.ConnectionString =   Provider = Microsoft.Jet.OLEDB.4.0; Data Source = & App.Path&   \Database1.mdb&  ; Persist Security Info = False; 
 
 cnn.Open 
 结束  Sub  

突出显示的代码：

 rs.Open  选择*来自tbluser其中uname ='& txtuser.Text&  '，cnn，adOpenStatic，adLockReadOnly 

我刚刚在Dim rs上添加了Module1.getconnected作为新的ADODB.Recordset并且它正在工作，但基于我复制的原始程序，没有Module1.getconnected

解决方案

如果您想检查该用户是否存在并使用 Button1_Click（）事件，请尝试以下方法：

 私有  Sub  Button1_Click（...）
  Dim  cnn  As  ADODB.Connection 
  Dim  rs 作为 新 ADODB.Recordset 
 
 开 错误 转到 Err_Handler 
 
 ' 连接数据库 
 设置 cnn = 新 ADODB.Connection（）
 cnn.CursorLocation = adUseClient 
 cnn.ConnectionString =   Provider = Microsoft.Jet.OLEDB.4.0; Data Source =& App.Path&   \Database1.mdb&  ; Persist Security Info = False; 
 cnn.Open 
 ' 创建新记录集对象 
 设置 rs = 新 ADODB.Recordset（）
 rs.Open  选择*来自tbluser其中uname ='& txtuser.Text&  '，cnn，adOpenStatic，adLockReadOnly 
 如果 rs.RecordCount<>  1  然后 
 Msgbox  用户数：& rs.RecordCount，vbQuestion， 这怎么可能？ 
 转到 Exit_Sub 
 结束 如果 
 
 ' 只有一个用户!!!  
 ' 做你想做的事;） 
 MsgBox  < span class =code-string>欢迎！& vbCr&   Herzlich Willkomen！& vbCr&   Witaj！，vbInformation， 消息... 
 
 Exit_Sub：
 开启 错误 恢复 下一步 
 rs.Close 
 cnn.Close 
  Set  rs =  Nothing  
  set  cnn =  Nothing  
 退出  Sub  
 
 Err_Handler：
 Msgbox Err.Description，vbExclamation， < span class =code-string>错误& Err.Number 
 恢复 Exit_Sub 
 结束 子 

I always get this error everytime I ran the program.

Dim rs As New ADODB.Recordset
rs.Open "Select * From tbluser Where uname = '" & txtuser.Text & "'", cnn, adOpenStatic, adLockReadOnly
If rs.RecordCount < 1 Then
MsgBox "Invalid Username!", vbCritical, "Login Error"
txtuser.SetFocus
Exit Sub
Else
If txtpass.Text = rs!pword Then
Unload Me
Load Form2
Form2.Show
Exit Sub
Else
MsgBox "Invalid Password!", vbCritical, "Login Error"
txtpass.SetFocus
Exit Sub
End If
End If
Set rs = Nothing

MODULE CODE:

Option Explicit

Public cnn As ADODB.Connection
Public Sub getconnected()
  Set cnn = New ADODB.Connection
  cnn.CursorLocation = adUseClient
  cnn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\Database1.mdb" & ";Persist Security Info=False;"
  
  cnn.Open
    End Sub

THE HIGHLIGHTED CODE:

rs.Open "Select * From tbluser Where uname = '" & txtuser.Text & "'", cnn, adOpenStatic, adLockReadOnly

I just added Module1.getconnected on top of Dim rs As New ADODB.Recordset and it''s working but based on the original program that I copied there''s no Module1.getconnected

解决方案

If you want to check that user exists or not and you use Button1_Click() event, try this:

Private Sub Button1_Click(...)
Dim cnn As ADODB.Connection
Dim rs As New ADODB.Recordset

On Error Goto Err_Handler

'connect to database
Set cnn = New ADODB.Connection()
cnn.CursorLocation = adUseClient
cnn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\Database1.mdb" & ";Persist Security Info=False;"
cnn.Open
'create new recordset object
Set rs = New ADODB.Recordset()
rs.Open "Select * From tbluser Where uname = '" & txtuser.Text & "'", cnn, adOpenStatic, adLockReadOnly
If rs.RecordCount <> 1 Then
    Msgbox "Users count: " & rs.RecordCount, vbQuestion, "How is this possible?"
    Goto Exit_Sub
End If

'only one user!!!
'do what you want to do ;)
MsgBox "Welcome!" & vbCr & "Herzlich Willkomen!" &  vbCr & "Witaj!", vbInformation, "Message..."

Exit_Sub:
    On Error Resume Next
    rs.Close
    cnn.Close
    Set rs = Nothing
    set cnn = Nothing
    Exit Sub

Err_Handler:
    Msgbox Err.Description, vbExclamation, "Error " & Err.Number
    Resume Exit_Sub
End Sub

这篇关于VB6运行时错误3709连接不能用于执行操作 - 它关闭或无效的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！