SqlNotificationSource
Indicates the source of the notification received by the dependency event handler.
Client = -2
A client-initiated notification occurred, such as a client-side time-out or as a result of attempting to add a command to a dependency that has already fired.
Data = 0
Data has changed; for example, an insert, update, delete, or truncate operation occurred.
Database = 3
The database state changed; for example, the database related to the query was dropped or detached.
Environment = 6
The run-time environment was not compatible with notifications; for example, the isolation level was set to snapshot, or one or more SET options are not compatible.
Execution = 7
A run-time error occurred during execution.
Object = 2
A database object changed; for example, an underlying object related to the query was dropped or modified.
Owner = 8
Internal only; not intended to be used in your code.
Statement = 5
The Transact-SQL statement is not valid for notifications; for example, a SELECT statement that could not be notified or a non-SELECT statement was executed.
System = 4
A system-related event occurred. For example, there was an internal error, the server was restarted, or resource pressure caused the invalidation.
Timeout = 1
The subscription time-out expired.
Unknown = -1
Used when the source option sent by the server was not recognized by the client.