Re: merge on datasets from join queries

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From: Sahil Malik (contactmethrumyblog_at_nospam.com)
Date: 09/27/04 

Date: Mon, 27 Sep 2004 08:45:15 -0400

Glenn,

When you do A.Merge(B), it will not handle deleted rows out of the d/b,
because ... no information in B tells A that certain rows have been deleted.
You have to do that part manually. :-)

- Sahil Malik
You can reach me thru my blog -
http://www.dotnetjunkies.com/weblog/sahilmalik

"Glenn" <g.e.r@comcast.net> wrote in message
news:%236XF07IpEHA.1136@TK2MSFTNGP12.phx.gbl...
> Sahil:
>
> The source and destination datasets are being filled by the same stored
> procedure and have the same
> table name. Your comment that "Dataadapter.fill, will not by default pull
> in primary key
> information etc" pointed me in a helpful direction: the query is an outer
> join and Help said that you need to add a primary key for outer joins
> (they
> are not pulled in)
>
> This helped somewhat, now changes made by others are reflected and rows
> added by others are added, but for some reason rows not in the source
> dataset (either deleted by others or modifired so they do not meet the
> criteria of the original dataset) are not removed from the destination
> dataset.
>
> My scenario is that a user has a list of items, usually filtered by a
> status, from which he picks a record to load and edit. This list is
> refreshed periodically to reflect changes by other users. If another user
> has edited a displayed record so that it no longer meets the filter for
> the
> list, when the refresh is run and the record is no longer in the source
> dataset, I want it removed from the list. This is not happening on the
> merge.
>
> I guess I have to loop through and handle manually.
>
> Thanks for your help.
>
> Glenn
>
> "Sahil Malik" <contactmethrumyblog@nospam.com> wrote in message
> news:u5edkC$oEHA.3424@TK2MSFTNGP12.phx.gbl...
>> Glenn,
>>
>> If I understood correctly, Problem statement - "You want to refresh the
>> contents of your dataset with changes happening in the database".
>>
>> I believe you are on the right track for the solution. Consider the
>> following --
>>
>> a) Join queries are in the database, Dataset.Merge is in ADO.NET -- Two
>> different animals. We can simplify this situation by, "You are filling
>> the
>> dataset somehow".
>> b) Have you specified a primary key on the two Datatables (in ADO.NET)
>> you
>> are trying to merge within your datasets? More so, are the Datatable
>> names
>> the same? Dataadapter.fill, will not by default pull in primary key
>> information etc. There is a fillschema, method but my recommendation is
> not
>> to use that in a production application since that executes a fairly
>> heavy
>> query on your d/b.
>>
>> Dataset.Merge has pretty clearly laid out rules of how it will merge. And
>> yes it can be used to refresh data from the database (or anywhere else).
>>
>> - Sahil Malik
>> You can reach me thru my blog -
>> http://www.dotnetjunkies.com/weblog/sahilmalik
>>
>>
>>
>> "Glenn" <g.e.r@comcast.net> wrote in message
>> news:Oa36xl8oEHA.1988@TK2MSFTNGP09.phx.gbl...
>> >I have lookup/record selection grids bound to datasets with lists based
> on
>> > join queries. Periodically, I want to update these datasets to reflect
>> > changes made by other users. It seems the dataset.merge on the
>> > original
>> > dataset with a dataset of the refreshed records just duplicates the
>> > records.
>> > Although the list is a main table with PK and the other tables in the
> join
>> > query are just lookup values (leaving only one record per PK), the
> dataset
>> > merge does not work.
>> >
>> > Is this possible or is the only way to "refresh" a dataset based on a
>> > joined
>> > table to loop through and update each field? Note, I do not want to
> just
>> > re-fill the original dataset as it is bound to a grid and so all the
> event
>> > firing and other binding operations would be more difficult to handle.
>> >
>> > Thanks.
>> >
>> > Glenn
>> >
>> >
>>
>>
>
>

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