How many times have you needed to debug an application and wished, just wished, you had put better instrumentation in your code? It would have been brilliant if you had logged the key database fields before and after the update. It would have been killer if you had recognized exactly which rows and columns were in play and had a way of confirming that your stored proc is doing what you thought it would.

But you didn't.

Your app has no logging at all, and you have no ability to see what's happening in real-time other than firing up ol' SQL Server Management Studio and attempting to run queries before and after every action in your app. Now there is a better way.

SqlWatcher lets you use your web browser to query a SQL Server 2005/2008 database. Big deal so far. But after returning your results to you, SqlWatcher watches the database and notifies you instantly when your query results change, re-running your query and appending the latest results to your web browser as needed.

SqlWatcher does not poll for changes, nor does it leave a database connection open, both of which could hammer your database performance. It uses the power of SQL Server's Query Notifications to let the database engine itself track data changes that would impact your query results. Whether data was added, deleted, or modified, if it touches data that was in your results, or adds new data to it, Query Notifications sees it and pushes a notification out to a SqlDependency object in SqlWatcher. When SqlWatcher receives a notification, it re-runs your query and appends the latest results to your web browser, allowing you to see your query's results before and after every database change.

Query Notifications relies on SQL Server's Service Broker for reliable asynchronous delivery of these notifications to clients such as SqlWatcher. (It does not use Notification Services, which Microsoft removed from SQL Server 2008.) As a result, Service Broker must be enabled on the database you are trying to watch. If it's not, SqlWatcher will attempt to run ALTER DATABASE yourdatabase SET ENABLE_BROKER beforehand, and ALTER DATABASE yourdatabase SET DISABLE_BROKER afterwards, but you will need to provide administrator-level credentials in the connection string for this to work.

SqlWatcher was written in C# in Visual Studio 2008 and requires ASP.NET 2.0. It requires no database of its own but can watch any SQL Server 2005/2008 database with Service Broker enabled, or can enable it automatically with an admin-level connection string.