Selasa, 14 Agustus 2012

Re: [MS_AccessPros] Decreasing potential of "too many databases"

 

Hi Bill,

my understanding is that each linked tables DOES count as at least one connection -- more if there is RI

Warm Regards,
Crystal

http://www.YouTube.com/LearnAccessByCrystal

 *
   (: have an awesome day :)
 *

________________________________
From: Bill Mosca <wrmosca@comcast.net>
To: MS_Access_Professionals@yahoogroups.com
Sent: Tuesday, August 14, 2012 12:44 PM
Subject: Re: [MS_AccessPros] Decreasing potential of "too many databases"

Clive

I don't buy the idea that each linked table is a connection. It's really the number of connctions that counts. Unless you are retrieving rows or running DML ('action') queries, no connection is made. You can see that with the creation and destruction of the locking file.

If I remember right Windows XP can only handle 10 connections per user with a split DB. And I have applications that link to over 100 tables.

Regards,
Bill Mosca, Founder - MS_Access_Professionals
http://www.thatlldoit.com
Microsoft Office Access MVP
https://mvp.support.microsoft.com/profile=C4D9F5E7-BB03-4291-B816-64270730881E
My nothing-to-do-with-Access blog
http://wrmosca.wordpress.com

--- In MS_Access_Professionals@yahoogroups.com, "Clive" <zctek@...> wrote:
>
> Hi All,
>
> Afeter a bit more searching I found another link, this
> time for Access2003 and and illustrating the difference
> between using linked and local tables.
>
> http://bytes.com/topic/access/answers/472616-new-twist-too-many-databases-error
>
> Regards, Clive.
>
> --- In MS_Access_Professionals@yahoogroups.com, "Clive" <zctek@> wrote:
> >
> > Hi All,
> >
> > Here is a link that sheds some more light on the subject
> > even though it was for an earlier version of Access:
> >
> > http://www.office-archive.com/23-ms-access/037cc99c3e46753c.htm
> >
> > And another link that provides a solution if you are using
> > Privacy Manager for HP Protect Tools:
> >
> > http://msmvps.com/blogs/access/
> >
> > Regards, Clive.
> >
> > --- In MS_Access_Professionals@yahoogroups.com, Liz Ravenwood <liz_ravenwood@> wrote:
> > >
> > > :-)
> > >
> > > Liz Ravenwood
> > > Programmer/Analyst
> > > Super First Class Products
> > > B/E Aerospace
> > > O: 1.520.239.4808
> > > www.beaerospace.com
> > >
> > >
> > > -----Original Message-----
> > > From: MS_Access_Professionals@yahoogroups.com [mailto:MS_Access_Professionals@yahoogroups.com] On Behalf Of John Viescas
> > > Sent: Monday, August 13, 2012 1:35 PM
> > > To: MS_Access_Professionals@yahoogroups.com
> > > Subject: RE: [MS_AccessPros] Decreasing potential of "too many databases"
> > >
> > > Not in this case.  She's already setting db = CurrentDb and then not releasing
> > > it.  If you're gonna set it, might as well use it.  I agree for a "one off,"
> > > it's OK to use CurrentDb.Execute.
> > >
> > > John Viescas, author
> > > Microsoft Office Access 2010 Inside Out
> > > Microsoft Office Access 2007 Inside Out
> > > Building Microsoft Access Applications
> > > Microsoft Office Access 2003 Inside Out
> > > SQL Queries for Mere Mortals
> > > http://www.viescas.com/
> > > (Paris, France)
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: MS_Access_Professionals@yahoogroups.com
> > > [mailto:MS_Access_Professionals@yahoogroups.com] On Behalf Of Liz Ravenwood
> > > Sent: Monday, August 13, 2012 10:23 PM
> > > To: 'MS_Access_Professionals@yahoogroups.com'
> > > Subject: RE: [MS_AccessPros] Decreasing potential of "too many databases"
> > >
> > > Bill, me too.
> > >
> > > Liz Ravenwood
> > > Programmer/Analyst
> > > Super First Class Products
> > > B/E Aerospace
> > > O: 1.520.239.4808
> > > www.beaerospace.com
> > >
> > >
> > > -----Original Message-----
> > > From: MS_Access_Professionals@yahoogroups.com
> > > [mailto:MS_Access_Professionals@yahoogroups.com] On Behalf Of Bill Mosca
> > > Sent: Monday, August 13, 2012 1:16 PM
> > > To: MS_Access_Professionals@yahoogroups.com
> > > Subject: Re: [MS_AccessPros] Decreasing potential of "too many databases"
> > >
> > > Liz
> > >
> > > I disagree with John. When it comes to one execution and you're done I use
> > > CurrentDB.Execute.
> > >
> > > Bill Mosca
> > >
> > > --- In MS_Access_Professionals@yahoogroups.com, Liz Ravenwood
> > > <liz_ravenwood@> wrote:
> > > >
> > > > John, why?  Even if you're just going to do a one line deal?
> > > >
> > > > Liz Ravenwood
> > > > Programmer/Analyst
> > > > Super First Class Products
> > > > B/E Aerospace
> > > > O: 1.520.239.4808
> > > > www.beaerospace.com
> > > >
> > > > -----Original Message-----
> > > > From: MS_Access_Professionals@yahoogroups.com
> > > [mailto:MS_Access_Professionals@yahoogroups.com] On Behalf Of John Viescas
> > > > Sent: Monday, August 13, 2012 12:49 PM
> > > > To: MS_Access_Professionals@yahoogroups.com
> > > > Subject: RE: [MS_AccessPros] Decreasing potential of "too many databases"
> > > >
> > > > Connie-
> > > >
> > > > You should *never* IMHO use CurrentDb.Execute.  Always set a db object, the
> > > use
> > > > db.Execute.  Then Set db = Nothing before you exit.
> > > >
> > > > John Viescas, author
> > > > Microsoft Office Access 2010 Inside Out
> > > > Microsoft Office Access 2007 Inside Out
> > > > Building Microsoft Access Applications
> > > > Microsoft Office Access 2003 Inside Out
> > > > SQL Queries for Mere Mortals
> > > > http://www.viescas.com/
> > > > (Paris, France)
> > > >
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: MS_Access_Professionals@yahoogroups.com
> > > > [mailto:MS_Access_Professionals@yahoogroups.com] On Behalf Of mrsgoudge
> > > > Sent: Monday, August 13, 2012 9:43 PM
> > > > To: MS_Access_Professionals@yahoogroups.com
> > > > Subject: Re: [MS_AccessPros] Decreasing potential of "too many databases"
> > > >
> > > > Thanks John.  One more question--I'm going through my code and found the
> > > > following.  I have both db and CurrentDb.Execute.  What happens in this
> > > > case--Does CurrentDb.Execute open one more instance of the database in
> > > addition
> > > > to the one opened at Set db = CurrentDb?  If so, how would I change it?
> > > >
> > > > Thanks again!
> > > > Connie
> > > >
> > > > If response = vbYes Then
> > > >            'Initialize
> > > >              Set db = CurrentDb
> > > >            'Turn off the "are you sure you want to delete" message
> > > >            DoCmd.SetWarnings False
> > > >            Dim strSQL As String
> > > >            strSQL = "DELETE Withdrawn.* FROM Withdrawn WHERE Withdrawn.ListID
> > > =
> > > > " & Me.ListID & ";"
> > > >            CurrentDb.Execute strSQL, dbFailOnError
> > > >            'Turn the warning capability back on
> > > >            DoCmd.SetWarnings True
> > > >            'Save Record
> > > >            If Me.Dirty Then
> > > >                Me.Dirty = False
> > > >            End If
> > > >            'Set Current Listing to Yes
> > > >            Set rstL = db.OpenRecordset("SELECT * FROM Listings WHERE ListID =
> > > "
> > > > & Me.ListID & ";")
> > > >            rstL.Edit
> > > >            rstL("CurrentListing").Value = -1
> > > >            rstL.Update
> > > >            'Set Status to "For Sale"
> > > >            Forms!Listings.Status = "FOR SALE"
> > > >            DoCmd.Close acForm, "UndoWithdrawn", acSaveNo
> > > >
> > > >        End If
> > > >
> > > > --- In MS_Access_Professionals@yahoogroups.com, John Viescas <JohnV@> wrote:
> > > > >
> > > > > Connie-
> > > > >
> > > > > The "too many databases" is a mystery.  Me, I like to control what's going
> > > on,
> > > > > so I always assign CurrentDb to an object variable and then make sure I
> > > clear
> > > > it
> > > > > before exit.  With CurrentDb, you know you're always opening one more
> > > thread,
> > > > > then killing it when you Set db = Nothing.  I dunno what happens with a
> > > > > reference to DBEngine.
> > > > >
> > > > > John Viescas, author
> > > > > Microsoft Office Access 2010 Inside Out
> > > > > Microsoft Office Access 2007 Inside Out
> > > > > Building Microsoft Access Applications
> > > > > Microsoft Office Access 2003 Inside Out
> > > > > SQL Queries for Mere Mortals
> > > > > http://www.viescas.com/
> > > > > (Paris, France)
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > -----Original Message-----
> > > > > From: MS_Access_Professionals@yahoogroups.com
> > > > > [mailto:MS_Access_Professionals@yahoogroups.com] On Behalf Of mrsgoudge
> > > > > Sent: Monday, August 13, 2012 9:14 PM
> > > > > To: MS_Access_Professionals@yahoogroups.com
> > > > > Subject: Re: [MS_AccessPros] Decreasing potential of "too many databases"
> > > > >
> > > > > John - That is code I copied from Allen Browne's site.  Should I be changing
> > > > > that?  Any idea why Crystal would experience a decrease in the "cannot open
> > > > > databases" messages using DBEngine(0)(0)?
> > > > >
> > > > > Thanks!
> > > > > Connie
> > > > >
> > > > > --- In MS_Access_Professionals@yahoogroups.com, John Viescas <JohnV@> wrote:
> > > > > >
> > > > > > Connie-
> > > > > >
> > > > > > Why are you using DBEngine(0)(0)?  I would declare a db object As
> > > > > DAO.Database,
> > > > > > set it to CurrentDb, then release it in your exit code.
> > > > > >
> > > > > > John Viescas, author
> > > > > > Microsoft Office Access 2010 Inside Out
> > > > > > Microsoft Office Access 2007 Inside Out
> > > > > > Building Microsoft Access Applications
> > > > > > Microsoft Office Access 2003 Inside Out
> > > > > > SQL Queries for Mere Mortals
> > > > > > http://www.viescas.com/
> > > > > > (Paris, France)
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > -----Original Message-----
> > > > > > From: MS_Access_Professionals@yahoogroups.com
> > > > > > [mailto:MS_Access_Professionals@yahoogroups.com] On Behalf Of mrsgoudge
> > > > > > Sent: Monday, August 13, 2012 8:03 PM
> > > > > > To: MS_Access_Professionals@yahoogroups.com
> > > > > > Subject: [MS_AccessPros] Decreasing potential of "too many databases"
> > > > > >
> > > > > > Good afternoon!  Evening to you, John!
> > > > > >
> > > > > > I am working on getting rid of the "too many databases" message again and
> > > > > doing
> > > > > > my best to decrease the chances it will crop up.  From some reading I've
> > > > done,
> > > > > > it seems that using the following function in a query could be a major
> > > > > > contributor.  Yes?  when I do get the "too many databases" message
> > > debugging
> > > > > > shows that it's usually stopped at this point.
> > > > > >
> > > > > > I'm considering putting the result in the underlying table.  For example,
> > > > once
> > > > > > the listers are entered and the ListingContacts form is closed this would
> > > be
> > > > > > entered for that listing in
> > > > > > Listings.AllContacts.
> > > > > >
> > > > > > Input?  I know this doesn't really follow the rules but I can only see the
> > > > > > benefits.
> > > > > >
> > > > > > Thanks,
> > > > > > Connie
> > > > > >
> > > > > >
> > > > > > Public Function ConcatRelated(strField As String, _
> > > > > >                              strTable As String, _
> > > > > >                              Optional strWhere As String, _
> > > > > >                              Optional strOrderBy As String, _
> > > > > >                              Optional strSeparator = ", ") As Variant
> > > > > >    On Error GoTo Err_Handler
> > > > > >    'Purpose:  Generate a concatenated string of related records.
> > > > > >    'Return:    String variant, or Null if no matches.
> > > > > >    'Arguments: strField = name of field to get results from and
> > > > concatenate.
> > > > > >    '          strTable = name of a table or query.
> > > > > >    '          strWhere = WHERE clause to choose the right values.
> > > > > >    '          strOrderBy = ORDER BY clause, for sorting the values.
> > > > > >    '          strSeparator = characters to use between the concatenated
> > > > > > values.
> > > > > >    'Notes:    1. Use square brackets around field/table names with
> > > spaces
> > > > or
> > > > > > odd characters.
> > > > > >    '          2. strField can be a Multi-valued field (A2007 and later),
> > > > but
> > > > > > strOrderBy cannot.
> > > > > >    '          3. Nulls are omitted, zero-length strings (ZLSs) are
> > > > returned
> > > > > as
> > > > > > ZLSs.
> > > > > >    '          4. Returning more than 255 characters to a recordset
> > > > triggers
> > > > > > this Access bug:
> > > > > >    '              http://allenbrowne.com/bug-16.html
> > > > > >    Dim rs As DAO.Recordset                          'Related records
> > > > > >    Dim rsMV As DAO.Recordset                        'Multi-valued field
> > > > > > recordset
> > > > > >    Dim strSQL As String                              'SQL statement
> > > > > >    Dim strOut As String                              'Output string to
> > > > > > concatenate to.
> > > > > >    Dim lngLen As Long                                'Length of string.
> > > > > >    Dim bIsMultiValue As Boolean                      'Flag if strField is
> > > a
> > > > > > multi-valued field.
> > > > > >
> > > > > >    'Initialize to Null
> > > > > >    ConcatRelated = Null
> > > > > >
> > > > > >    'Build SQL string, and get the records.
> > > > > >    strSQL = "SELECT " & strField & " FROM " & strTable
> > > > > >    If strWhere <> vbNullString Then
> > > > > >        strSQL = strSQL & " WHERE " & strWhere
> > > > > >    End If
> > > > > >    If strOrderBy <> vbNullString Then
> > > > > >        strSQL = strSQL & " ORDER BY " & strOrderBy
> > > > > >    End If
> > > > > >    Set rs = DBEngine(0)(0).OpenRecordset(strSQL, dbOpenDynaset)
> > > > > >    'Determine if the requested field is multi-valued (Type is above 100.)
> > > > > >    bIsMultiValue = (rs(0).Type > 100)
> > > > > >
> > > > > >    'Loop through the matching records
> > > > > >    Do While Not rs.EOF
> > > > > >        If bIsMultiValue Then
> > > > > >            'For multi-valued field, loop through the values
> > > > > >            Set rsMV = rs(0).Value
> > > > > >            Do While Not rsMV.EOF
> > > > > >                If Not IsNull(rsMV(0)) Then
> > > > > >                    strOut = strOut & rsMV(0) & strSeparator
> > > > > >                End If
> > > > > >                rsMV.MoveNext
> > > > > >            Loop
> > > > > >            Set rsMV = Nothing
> > > > > >        ElseIf Not IsNull(rs(0)) Then
> > > > > >            strOut = strOut & rs(0) & strSeparator
> > > > > >        End If
> > > > > >        rs.MoveNext
> > > > > >    Loop
> > > > > >    rs.Close
> > > > > >
> > > > > >    'Return the string without the trailing separator.
> > > > > >    lngLen = Len(strOut) - Len(strSeparator)
> > > > > >    If lngLen > 0 Then
> > > > > >        ConcatRelated = Left(strOut, lngLen)
> > > > > >    End If
> > > > > >
> > > > > > Exit_Handler:
> > > > > >    'Clean up
> > > > > >    Set rsMV = Nothing
> > > > > >    Set rs = Nothing
> > > > > >    Exit Function
> > > > > >
> > > > > > Err_Handler:
> > > > > >    MsgBox "Error " & Err.Number & ": " & Err.Description, _
> > > > > >            vbExclamation, "ConcatRelated()"
> > > > > >    Resume Exit_Handler
> > > > > > End Function
> > > > > >
> > > > > >
> > > > > >
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