BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  cancel during asyncfetchnonblocking          BorlandTalk.com Forum Index -> Delphi Databases (ADO) View previous topic :: View next topic   Author Message Lutz Kutscher Guest Posted: Tue Aug 17, 2004 7:27 pm    Post subject: cancel during asyncfetchnonblocking Hi, I wanted to use the ExecuteOption eoAsyncFetchNonBlocking to build a progressive filtering form: In the OnShow event of my form I open a query on a large table (20,000+ records): "select * from HugeTable" Since it is opened in non blocking mode, the user can enter a search string into a TEdit control. The OnChange of that TEdit looks like this: TMyForm.Edit1Change(Sender: TObject); begin AdoDS.Close; AdoDS.CommandText := 'select * from HugeTable where SearchField=''' + Edit1.Text + ''''; AdoDS.Open; end; The problem with this seems to be, that the query is not really cancelled with the AdoDS.Close - looking at my memory usage it climbs incredibly. I tried using the OnFetchProgress event to set EventStatus to esCancel - the name and declaration as var parameter sounded like it could work - nothing. Can anyone around here tell me, how to really tell ADO to stop loading the data that isn't needed any longer? Thanks a lot Lutz Back to top Martijn Tonies Guest Posted: Wed Aug 18, 2004 7:28 am    Post subject: Re: cancel during asyncfetchnonblocking Quote: AdoDS.Close; AdoDS.CommandText := 'select * from HugeTable where SearchField=''' + Edit1.Text + ''''; AdoDS.Open; end; The problem with this seems to be, that the query is not really cancelled with the AdoDS.Close - looking at my memory usage it climbs incredibly. I tried using the OnFetchProgress event to set EventStatus to esCancel - the name and declaration as var parameter sounded like it could work - nothing. Can anyone around here tell me, how to really tell ADO to stop loading the data that isn't needed any longer? Try AdoDS.Recordset.Cancel; AdoDS.Close; Did you test this? Can you use the same object for another query? I've been spending quite some time with all sorts of settings but can't seem to get this working in an OK manner. -- With regards, Martijn Tonies Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL Server. Upscene Productions http://www.upscene.com Back to top Lutz Kutscher Guest Posted: Wed Aug 18, 2004 5:35 pm    Post subject: Re: cancel during asyncfetchnonblocking On Tue, 17 Aug 2004 20:08:37 -0500, Brian Bushay TeamB <BBushay (AT) Nmpls (DOT) com> wrote: Quote: AdoDS.Recordset.Cancel; AdoDS.Close; Hey, great, thanks. I just didn't realize the possibilities the direct access to the RecordSet object opens. - It would have been nicer though, had the delphi developers integrated that feature into the delphi implementation of ADO. The reason I didn't find it, was mainly, that I tried to find something in the Delphi help on TAdoDataSet and forgot to look into Microsoft's help. Well, anyway, you made my day. Lutz Back to top Martijn Tonies Guest Posted: Thu Aug 19, 2004 2:27 pm    Post subject: Re: cancel during asyncfetchnonblocking Hi Brian, Quote: AdoDS.Recordset.Cancel; AdoDS.Close; Did you test this? Not with the code posted Can you use the same object for another query? I do not understand your question I've been trying to get such a cancel -- running the ado stuff in a thread, cancelling from the main thread. Although I could get it to cancel, the following could happen: - it kept on loading data into the local memory or - it cancelled just fine, but running a query in the same command object failed horribly All in all, I can't say it actually works. -- With regards, Martijn Tonies Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL Server. 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