Re: IRowsetResynch/IRowsetRefresh

Mark,

It might be quite pedestrian but a simple way is to include a timestamp
field in each updatable table. Note: I'm talking about the SQL hexidecimal
datatype not a simple datetime field. Every query to the database should
bring this back to the client. On any update operation (inc. delete) the
timestamp in the database is compared with the timestamp from the client. If
the two are not the same, then the row has changed.

James

-----Original Message-----
From: Mark Dawson [mailto:[email protected]]
Sent: 05 06 2002 15:05
To: [email protected]
Subject: Re: [OLEDB_DEV] IRowsetResynch/IRowsetRefresh


Thanks for correcting me Bob,

Shame though, I think Microsoft missed a trick there - the amount of clients
who are intersted in changes made by other people must be significant.

One way round it I thought of in the past (but never got round to trying)
was to have all updates pass through stored procedures.  These SPs could
then invoke a COM object (via the sp_OA* SPs) which posted a message to a
well known message queue.  Interested clients can then just connect to the
message queue and listen for events.  Of course things have moved on since
this idea was conceived and other technologies such as the COM+ event system
might be more appropriate than message queue.

Has anyone else implemented or thought of possible solutions to this?  I'd
be interested to hear them.

Mark
--------------------------------------------------------------
Mark Dawson ([email protected])
Software Project Leader
Schenck Test Automation Ltd.
Lowesmoor Wharf, Worcester.
WR1 2RS. UK
+44 (0)1905 613361


-----Original Message-----
From: Beauchemin, Bob [mailto:[email protected]]
Sent: 05 June 2002 14:56
To: [email protected]
Subject: Re: [OLEDB_DEV] IRowsetResynch/IRowsetRefresh


IRowsetNotify is to notify listeners in the same process (for example,
notify a chart control that a grid control's data in the same process has
changed. You won't get notifications from the database using this.

OTOH, unless you have a server cursor, and, in some cases, a transaction,
you won't get any rows from IRowsetResync/Refresh polling the database
either.

Bob Beauchemin
[email protected]


        -----Original Message-----
        From: Mark Dawson [mailto:[email protected]]
        Sent: Wed 6/5/2002 1:04 AM
        To: [email protected]
        Cc:
        Subject: Re: [OLEDB_DEV] IRowsetResynch/IRowsetRefresh



        You'd be better off using the IRowsetNotify events interface as this
will
        inform you of changes instead of you polling the DB.
        I haven't used the event notifications but there's plenty in the
help about
        them.

        Cheers,
        Mark
        --------------------------------------------------------------
        Mark Dawson ([email protected])
        Software Project Leader
        Schenck Test Automation Ltd.
        Lowesmoor Wharf, Worcester.
        WR1 2RS. UK
        +44 (0)1905 613361


        -----Original Message-----
        From: Massimiliano Alberti [mailto:[email protected]]
        Sent: 02 June 2002 18:25
        To: [email protected]
        Subject: [OLEDB_DEV] IRowsetResynch/IRowsetRefresh


        Can someone give me a working example of one of these two
interfaces? I
        need to do a query to the DBMS (SQL Server 2000) and then every X
seconds
        (where X is customizable) I want to ask to the DBMS if there are
        new/modified rows...

        Bye
        Max

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