其他部分的代码保持超时

Question

我有一个代码来打开表单时检查访问和sql server之间的连接。如果有连接，则弹出一个消息框并说明。如果没有，应该有一个消息框指示没有连接。相反，我得到的错误：

Run Time Error '-2147467259 (80004005)': 
[DBNETLIB][ConnectionOpen (Connect()).]Specified SQL Server Not Found 

这是不是我想要它做的事，是东西在我的编码或者是有没有办法得到这个工作？

Public Sub AutoExec() 
Dim cnn As ADODB.Connection 
Dim localrst As New ADODB.Recordset 
Dim remoterst As New ADODB.Recordset 

Set cnn = New ADODB.Connection 
cnn.Open "Provider=SQLOLEDB; Data Source=DB; Initial Catalog=HRLearnDev;" _ 
& "User Id=ID; Password=PW;" 

If cnn.State = adStateOpen Then 

MsgBox ("You have an established connection with the L&TD SQL Server Database.") 
Else 
MsgBox ("Cannot connect to remote server. Data will be stored locally to CDData Table until application is opened again.") 

End If 

cnn.Close 



End Sub 

Answer 1

在这样的情况下，你通常要使用On Error GoTo结构 - 如果发生错误，然后将代码发送到您的错误处理程序（可以测试，以确保该错误号是您期望与Err.Num什么） 。

但是，在你的情况下，它可能更容易使用On Error Resume Next。这告诉解释者“如果发生错误，请转到下一行，我会弄清楚出了什么问题并处理它。”

通常，当您有一个函数调用会产生错误或合理的值时，您会这样做。我经常这样做：

On Error Resume Next 
returnValue = -1 
returnValue = functionThatReturnsPositiveValue() 
If returnValue < 0 Then 
    MsgBox "oops - the function failed!" 
Else 
    ' <<<< do whatever needs doing >>>> 
End If 

在你的情况下，这几乎就是你会做的。完整示例：

Public Sub AutoExec() 
    Dim cnn As ADODB.Connection 
    Dim localrst As New ADODB.Recordset 
    Dim remoterst As New ADODB.Recordset 

    On Error Resume Next   ' <<<<<< add this line so an error doesn't stop the code 
    Set cnn = New ADODB.Connection 
    cnn.State = 0 ' <<<<< not sure if you need something like this, or if the New command 
         already set it to some sensible value other than "adStateOpen" 

    cnn.Open "Provider=SQLOLEDB; Data Source=DB; Initial Catalog=HRLearnDev;" _ 
    & "User Id=ID; Password=PW;" 

    If cnn.State = adStateOpen Then  ' <<<<<< this will only be true if no error occurred 
    MsgBox ("You have an established connection with the L&TD SQL Server Database.") 
    Else 
    MsgBox ("Cannot connect to remote server. Data will be stored locally to CDData Table until application is opened again.") 
    End If 
    On Error GoTo 0  ' <<<<<<<< turn off error handling - we have passed the "tricky" spot. 

' <<<<<< lots more code goes here >>>>>> 

    If cnn.State = adStateOpen Then cnn.Close ' <<<<<<<< only close connection if it was open!! 

End Sub