Set Active to true to start monitoring the communication between SQLConnection and its database server. Set Active to false to stop the monitoring. 

When you set Active to true, TSQLMonitor sets the TraceCallbackEvent property of the associated SQL connection component. This causes all commands sent to the database server that match the criteria established by TraceFlags to be added to the monitor's string list. 

When you set Active to false, TSQLMonitor clears the TraceCallbackEvent property of the associated SQL connection component. No subsequent commands are added to TraceList, but the list is not cleared. That is, any commands currently in the list remain there until you explicitly clear the list. 

TraceCallbackEvent 

SQLConnection 

TraceList 

TraceFlags 

Debugging dbExpress Applications 

Fetching the Data using TSQLDataSet 

Using TSimpleDataSet 

Using TSQLQuery 

Using TSQLStoredProc