Question

这可能是我曾经遇到过的最混乱的错误。

这里有一些会产生错误的VB代码。我并不感兴趣我不必创建新的记录集，这是故意触发错误。

Public Module ConnectionSetup

Public ActiveTDConnection As ADODB.Connection

Public Sub ConnectToTD(ByVal userName As String, ByVal Password As String, ByVal dsn As String)

    ActiveTDConnection = New ADODB.Connection

    ActiveTDConnection.ConnectionString = "Provider=MSDASQL.1;Persist Security Info=True;" & _

              "User ID=" & userName & ";Password=" & Password & ";" & _

              "Data Source=" & dsn & ";Mode=Read;" & _

              "UID=" & userName & ";AUTHENTICATION=LDAP;Initial Catalog=(Default)"

    ActiveTDConnection.CommandTimeout = 0

    ActiveTDConnection.Open(ActiveTDConnection.ConnectionString)

End Sub

End Module

Module Module1

 Sub Main()

    ConnectionSetup.ConnectToTD("XXX", "XXX", "XXX")


    Dim DB_qry As String

    Dim sessionQry As String

    Dim i As Integer = 1

    Dim sessionRS As New ADODB.Recordset


    DB_qry = "SELECT TOP 1 * FROM dbc.databases"

    sessionQry = "SELECT COUNT(*) FROM dbc.SessionInfo WHERE userName = 'MyUserName'"


    Do While i <= 18

        Dim DB_rs As New ADODB.Recordset

        DB_rs.Open(DB_qry, ActiveTDConnection)

        sessionRS.Open(sessionQry, ActiveTDConnection)

        ' This starts going up by 1 on each loop, after 16.
        Debug.Print(sessionRS.Fields.Item(0).Value)

        Do While Not DB_rs.EOF

            MsgBox(i)

            i += 1

            DB_rs.MoveNext()

        Loop

        DB_rs.Close()

        DB_rs = Nothing

        sessionRS.Close()

     Loop

 End Sub

在第16次迭代之后，每个新打开的recordSet都会产生一个新连接。所以我的代码随机开始冒着最大限度地超出会话限制的风险。

1。）为什么会这样？

2.。我该如何预防？

Answer 1

 Sub Main()

    ConnectionSetup.ConnectToTD("XXX", "XXX", "XXX")


    Dim DB_qry As String
    Dim sessionQry As String

    Dim i As Integer = 1

    Dim sessionRS As New ADODB.Recordset

    DB_qry = "SELECT SESSION"

    sessionQry = "SELECT COUNT(*) FROM dbc.SessionInfo WHERE userName = 'MyUserName'"


    Do While i <= 18

        Dim DB_rs As New ADODB.Recordset

        DB_rs.Open(DB_qry, ActiveTDConnection)

        sessionRS.Open(sessionQry, ActiveTDConnection)

        ' This starts going up by 1 on each loop, after 16.
        'Debug.Print(sessionRS.Fields.Item(0).Value)

        Do While Not DB_rs.EOF

            MsgBox("Sessions: " & sessionRS.Fields.Item(0).Value & " Cnt: " & i & " SID: " & DB_rs.Fields.Item(0).Value)

            i += 1

            DB_rs.MoveNext()

        Loop

        DB_rs.Close()
        DB_rs = Nothing
        sessionRS.Close()

     Loop

 End Sub

ADO记录集在16次创建后开始建立新连接

1 个答案: