[fpc-pascal] Coping a DataSet

[silvioprog]

dbExpress, IBQuery or Zeos implements it?


2012/12/3 Marcos Douglas <md at delfire.net>

> On Mon, Dec 3, 2012 at 2:32 PM, Michael Van Canneyt
> <michael at freepascal.org> wrote:
> >
> >
> > On Mon, 3 Dec 2012, Marcos Douglas wrote:
> >
> >> On Mon, Dec 3, 2012 at 2:03 PM,  <michael.vancanneyt at wisa.be> wrote:
> >>>
> >>>
> >>>
> >>> On Mon, 3 Dec 2012, silvioprog wrote:
> >>>
> >>>> Guys,
> >>>>
> >>>> Is "Assign" method implemented for dataset in FPC?
> >>>
> >>>
> >>>
> >>> No, it is not. Datasets differ wildly in how they access and store
> data.
> >>>
> >>> Michael.
> >>
> >>
> >> But all descendents use TFieds classes so, why not?
> >> I can use a loop and the Append method, but this is not faster.
> >
> >
> > Speed is not the issue.
> >
> > There is simply no way to tell what this action will do behind the
> scenes.
> >
> > You might for example generate a huge amount of queries, which will
> > presumably all fail, since the records already exist in the database.
>
> I guess I didn't understand you, sorry (thanks for the patience).
> I'm talking about copy the data only in memory. Do not is necessary
> check if record already exists.
>
> > Then: Should the transaction be copied ? etc. etc. etc.
> >
>
> I want, eg., copy a TZQuery (Zeos) to a TSQLQuery or TBufDataSet.
>
> > In short: it is not implemented, and I doubt it every will be, at least
> at
> > the TDataset level.
>
> I see.
> Well, I wont to compare, but C# have ds.Copy and ds.Clone. I needed
> something like that.
> http://msdn.microsoft.com/en-us/library/system.data.dataset.copy.aspx
>
> > When using a pure TBufDataset, probably it is possible to copy the data
> > package
> > (much like TClientDataset in Delphi), but this would need to be
> implemented.
>
> Yes, like a TClientDataSet -- but I think this code is in midas.dll.
> The ClientDataSet copy data from whatever TDataSet descendent to him
> and this is fast.
>
> Marcos Douglas


-- 
Silvio Clécio
My public projects - github.com/silvioprog
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