Question

求助:VB运行时错误\"3704\",对象关闭时,不允许操作

这是修改用户密码的代码：
Private Sub Command1_Click()
Dim Rs As New ADODB.Recordset
Dim sql As String
Dim sql2 As String
If Text1.Text = "" Or Text2.Text = "" Or Text3.Text = "" Or Text4.Text = "" Then
MsgBox "输入的信息不完全,请输入完整的信息!", , "提示"
Exit Sub
End If
O
sql = "select * from us where u ='" & Text1.Text & "' and p ='" & Text2.Text & "'"
Rs.Open sql, Cn, adOpenDynamic, adLockPessimistic
If Rs.EOF = True Then
MsgBox "用户密码不匹配,无权更改!", vbOKOnly + vbExclamation, "警告"
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""
Text4.Text = ""
Text1.SetFocus
Exit Sub
Else
If Text3.Text <> Text4.Text Then
MsgBox "两次输入的新密码不同!", vbOKOnly, "询问"
Text3.Text = ""
Text4.Text = ""
Text3.SetFocus
Else
sql2 = "select * from us where u ='" & Text1.Text & "'"
Rs!u = Text1.Text
Rs!p = Text3.Text
If Check1.Value = 1 Then
Rs!T = True
Else
Rs!T = False
End If
Rs.Update
cL
MsgBox "密码修改成功!", vbOKOnly, "修改密码"
Me.Hide
End If
End If

End Sub
Public Sub O()
Cn.ConnectionString = "provider=Microsoft.jet.oledb.4.0;data source=" & App.Path & "\db1.mdb;"
Cn.Open
End Sub
Public Sub cL()
Rs.Close
Cn.Close
Set Rs = Nothing
Set Cn = Nothing
End Sub
运行时提示错误， Rs.Close一句变黄。

Answer 1

Private Sub Command1_Click() 中问题比较多，问题不在于 cL() 过程：
1、输入数据的判断必须放在打开数据库和数据表之前，我对你的程序修改了一下，应该不存在问题了：

Private Sub Command1_Click()
Dim Rs As New ADODB.Recordset
Dim sql As String
Dim sql2 As String
If Text1.Text = "" Or Text2.Text = "" Or Text3.Text = "" Or Text4.Text = "" Then
MsgBox "输入的信息不完全,请输入完整的信息!", 48, "提示"
Exit Sub
End If
If Text3.Text <> Text4.Text Then '数据输入判断应该在打开数据库之前。
MsgBox "两次输入的新密码不同!", vbOKOnly, "询问"
Text3.Text = ""
Text4.Text = ""
Text3.SetFocus
Exit Sub
End If
Call O '调用打开数据库
sql = "select * from us where u ='" & Text1.Text & "' and p ='" & Text2.Text & "'"
Rs.Open sql, Cn, adOpenDynamic, adLockPessimistic
If Rs.EOF = True Then
MsgBox "用户名或密码不正确,你无权更改!", 16, "警告"
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""
Text4.Text = ""
Text1.SetFocus
Call cL ‘在结束过程前必须关闭记录集对象和数据库对象，调用过程必须使用关键字 Call
Exit Sub
Else
Rs!u = Text1.Text
Rs!p = Text3.Text
If Check1.Value = 1 Then
Rs!T = True
Else
Rs!T = False
End If
Rs.Update
Call cL
MsgBox "密码修改成功!", vbOKOnly, "修改密码"
Me.Hide
End If
End Sub

Public Sub O() '数据库调用过程
Cn.ConnectionString = "provider=Microsoft.jet.oledb.4.0;data source=" & App.Path & "\db1.mdb;"
Cn.Open
End Sub

Public Sub cL() '关闭记录集对象和数据库对象过程
Rs.Close
Cn.Close
Set Rs = Nothing
Set Cn = Nothing
End Sub

Answer 2

定义RS为公有变量，也就是在代码最前面定义。然后如下判断

If Rs.State = 1 Then Rs.Close
关闭前先判断是否打开，打开则执行关闭，否则不执行。还有 open也一样 最好先判断是否是关闭状态再打开，如果已经打开了你再open就出错了。

Answer 3

rs对象作用范围只是在Command1_Click()事件里
和Public Sub cL()
Rs.Close
里的rs对象不是同一个 所以cl里的rs没open却close当然出错

追问

那应该怎改呢？

追答

Dim Rs As New ADODB.Recordset
放到最外面

Answer 4

Rs是在Command1里声明的，而Sub cL()里的Rs没有显式的声明，跟Command1的Rs不是一个，因为根本就没打开，所以关闭的时候会出错。
避免这种声明的错误，可以在代码的最前面加上
Option Explicit
强制声明变量的语句，这样可以避免类似上面的这种隐性的错误。