问题
So, I've been asked to update an old Classic ASP website. It did not use parameterized queries and there was very little input validation. To simplify things I wrote a helper function that opens a connection to the database, sets up a command object with any parameters, and creates a disconnected recordset [I think!?! :)] Here's the code:
Function GetDiscRS(DatabaseName, SqlCommandText, ParameterArray)
'Declare our variables
Dim discConn
Dim discCmd
Dim discRs
'Build connection string
Dim dbConnStr : dbConnStr = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=" & rootDbPath & "\" & DatabaseName & ".mdb;" & _
"Persist Security Info=False"
'Open a connection
Set discConn = Server.CreateObject("ADODB.Connection")
discConn.Open(dbConnStr)
'Create a command
Set discCmd = Server.CreateObject("ADODB.Command")
With discCmd
Set .ActiveConnection = discConn
.CommandType = adCmdText
.CommandText = SqlCommandText
'Attach parameters to the command
If IsArray(ParameterArray) Then
Dim cnt : cnt = 0
For Each sqlParam in ParameterArray
discCmd.Parameters(cnt).Value = sqlParam
cnt = cnt + 1
Next
End If
End With
'Create the Recordset object
Set discRs = Server.CreateObject("ADODB.Recordset")
With discRs
.CursorLocation = adUseClient ' Client cursor for disconnected set
.LockType = adLockBatchOptimistic
.CursorType = adOpenForwardOnly
.Open discCmd
Set .ActiveConnection = Nothing ' Disconnect!
End With
'Return the Recordset
Set GetDiscRS = discRS
'Cleanup
discConn.Close()
Set discConn = Nothing
discRS.Close() ' <=== Issue!!!
Set discRs = Nothing
Set discCmd = Nothing
End Function
My problem is that if I call discRS.Close() at the end of the function, then the recordset that is returned is not populated. This made me wonder if the recordset is indeed disconnected or not. If I comment that line out everything works properly. I also did some Response.Write() within the function using discRS values before and after setting ActiveConnection = Nothing and it properly returned the recordset values. So it seems to be isolated to discRS.Close().
I found an old article on 4guysfromrolla.com and it issues the recordset Close() in the function. I've seen the same thing on other sites. I'm not sure if that was a mistake, or if something has changed?
Note: I'm using IIS Express built into Visual Studio Express 2013
回答1:
Disconnected recordset as far as I know refers to a recordset populated manually, not from database, e.g.used as multi dimensional array or kind of hash table.
So what you have is not a disconnected recordset since it's being populated from database, and by disposing its connection you just cause your code to not work properly.
Since you already have Set discConn = Nothing in the code you don't have to set it to nothing via the recordset or command objects, it's the same connection object.
To sum this all up, you should indeed get rid of tho following lines in your code:
Set .ActiveConnection = Nothing ' Disconnect!discRS.Close() ' <=== Issue!!!Set discRs = Nothing
Then to prevent memory leaks or database lock issues, you should close and dispose the recordset after actually using it in the code using the function e.g.
Dim oRS
Set oRS = GetDiscRS("mydatabase", "SELECT * FROM MyTable", Array())
Do Until oRS.EOF
'process current row...
oRS.MoveNext
Loop
oRS.Close ' <=== Close
Set oRS = Nothing ' <=== Dispose
To avoid all this hassle you can have the function return "real" disconnected recordset by copying all the data into newly created recordset. If relevant let me know and I'll come with some code.
回答2:
In your function, you cannot close and clean up your recordset if you want it to be returned to the calling process.
You can clean up any connections and command objects, but in order for your recordset to be returned back populated, you simply do not close it or dispose of it.
Your code should end like this:
'Cleanup
discConn.Close()
Set discConn = Nothing
'discRS.Close()
'Set discRs = Nothing
'Set discCmd = Nothing
end function
回答3:
In your code i can see:
Set .ActiveConnection = Nothing ' Disconnect!
So, this Recordset isn't already closed?
回答4:
He is indeed using a disconnected recordset. I started using them in VB6. You set the connection = Nothing and you basically have a collection class with all the handy methods of a recordset (i.e. sort, find, filter, etc....). Plus, you only hold the connection for the time it takes to fetch the records, so back when Microsoft licensed their servers by the connection, this was a nice way to minimize how many userm were connected at any one time.
The recordset is completely functional, it's just not connected to the data source. You can reconnect it and then apply any changes that were made to it.
It was a long time ago, it seems that functionality has been removed.
回答5:
You should use the CursorLocation = adUseClient. Then you can disconnect the recordset. I have created a function to add the parameters to command dictionary objects, and then return a disconnected recordset.
Function CmdToGetDisconnectedRS(strSQL, dictParamTypes, dictParamValues)
'Declare our variables
Dim objConn
Dim objRS
Dim Query, Command
Dim ParamTypesDictionary, ParamValuesDictionary
'Open a connection
Set objConn = Server.CreateObject("ADODB.Connection")
Set objRS = Server.CreateObject("ADODB.Recordset")
Set Command = Server.CreateObject("ADODB.Command")
Set ParamTypesDictionary = Server.CreateObject("Scripting.Dictionary")
Set ParamValuesDictionary = Server.CreateObject("Scripting.Dictionary")
Set ParamTypesDictionary = dictParamTypes
Set ParamValuesDictionary = dictParamValues
Query = strSQL
objConn.ConnectionString = strConn
objConn.Open
With Command
.CommandText = Query
.CommandType = adCmdText
.CommandTimeout = 15
Dim okey
For Each okey in ParamValuesDictionary.Keys
.Parameters.Append .CreateParameter(CStr(okey), ParamTypesDictionary.Item(okey) ,adParamInput,50,ParamValuesDictionary.Item(okey))
Next
.ActiveConnection = objConn
End With
objRS.CursorLocation = adUseClient
objRS.Open Command , ,adOpenStatic, adLockBatchOptimistic
'Disconnect the Recordset
Set objRS.ActiveConnection = Nothing
'Return the Recordset
Set CmdToGetDisconnectedRS = objRS
'Clean up...
objConn.Close
Set objConn = Nothing
Set objRS = Nothing
Set ParamTypesDictionary =Nothing
Set ParamValuesDictionary =Nothing
Set Command = Nothing
End Function
来源：https://stackoverflow.com/questions/23661430/classic-asp-disconnected-recordsets-issue