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Is it possible to know when and if the contents of certain tables in a database has changed? How can my SQL Server notify the client applications that the data was changed by another user? How to implement query notifications with dbGo ?
Do my clients need to poll the database, or is there a callback mechanism for this?
My client is a Delphi application with TADODataSet, and my server is SQL Server 2005/2008, serving multiple clients.
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Database Change Notification is a feature that enables client applications to register queries with the database and receive notifications in response to DML or DDL changes on the objects associated with the queries. The notifications are published by the database when the DML or DDL transaction commits.
There are two simple methods within the NotificationsHub class, one to push the newly edited database table data to the clients (all the connected clients in this case), and a method to retrieve cached data when a device connects for the first time (performance gain).
The server returns each requested page (and possibly others) to the client. The client is responsible for mapping between objects and pages. In an object server system, the client requests specific objects from the server; the server is responsible for mapping between objects and pages.
Which of the following packages will you use when you want an application to be notified whenever the values of interest in the database are changed? Explanation/Reference: The DBMS_HPROF package provides an interface for profiling the execution of PL/SQL applications.
The Delphi dbGo controls does not support Query Notifications, so either poll the database or try to check e.g. some of the following:
WMI Provider for Server Events - MSSQL Service BrokerDA-SOFT AnyDAC TADEventAlerter component - Query Notifications mechanismDevart SDAC TMSChangeNotification component - Query Notifications mechanism
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