The event log is a generalized logging table that is located in a database, usually in a common area, and is available to applications, stored procedures, etc., that need a logging capability. There are also two stored procedures that provide logging and clearing interfaces.

The Event Log Viewer displays entries in the event_log that are written to meet an application's logging requirements, using either the LogEvent object or a stored procedure.

The event viewer encapsulates a TQuery and a TDataSource component, used to pull selected information from the event log. The TQuery's SQL text contains the column names and the event log database, which can be changed as required; this SQL text is retained as different queries are run while the event viewer is active.

Data is pulled from the event log by matching column values with settings made on the viewer's form. These are:

• Application An application mnemonic. If this is not specified, then matches can made against any entered mnemonic for which an application is defined in the log.
• Extension A logical subsection of the application. If a specified property, then only those extensions defined (as well as no extension) can be used to match entries in the event log.
• Type The functional type of event that was logged, such as ADDs, INFOrmation, etc. If any types are selected, then they constitute an assembled OR of all types. These event type descriptors are arbitrary, and can be assigned to meet an application's particular requirements.