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Learn How To Use The Oracle Continuous Query Notification (CQN) Feature With Delphi FireDAC On Windows

The Oracle_CQN sample shows you how to use Continuous Query Notification with Oracle databases using FireDAC.

Location

You can find the Oracle_CQN project at:

Description

To this end, this sample connects a client with CHANGE NOTIFICATION privilege to an Oracle database server and uses an event alerter to notify about database table data changes.

The implementation of this sample takes into account the following considerations listed in Oracle CQN section of the Data Change Notifications topic of FireDAC.

Files

File in DelphiContains
Oracle_CQN.dproj
Oracle_CQN.dpr
The project itself.
ChangeFrm.pas
ChangeFrm.dfm
The main form.

Implementation

Design Time

Before running the sample, the main components are configured at design time using the Object Inspector as follows:

Notes:

Run Time

When you run the application, you see the following components:

  1. Connects conOriginal and activates qOriginal.
  2. Connects conChanges with the same parameters than conOriginal
  3. Activates the eaChanges event alerter.
  4. Activates qOriginal.Note: As commented in the Description, you should activate TFDEventAlerter before executing the tracked TFDQuery.

Fore more information and official connections to other samples, follow the link below:

http://docwiki.embarcadero.com/CodeExamples/Sydney/en/FireDAC.Oracle_CQN_Sample

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