public bool HasChanges {get;}

'Declaration
 
Public ReadOnly Property HasChanges As Boolean

Property Value

If you are not using the OnChange event, you can check the HasChanges property to determine if the query results have changed.

Note that once the value of this property is set to true, it remains true forever. In other words, to continue tracking for changes you have to use the OnChange event or create another instance of the PgSqlDependency class.

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

PgSqlDependency Class
PgSqlDependency Members