When using SqlDependency & OnChangeEventHandler in .Net with SQL Server, is it possible (simple?) to discover what data has changed?
When using SqlDependency & OnChangeEventHandler in .Net with SQL Server, is it possible (simple?)
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When using SqlDependency & OnChangeEventHandler in .Net with SQL Server, is it possible (simple?) to discover what data has changed?
You need to run the query again and compare the result obtained with the previous result. How simple it is to detect exactly what changed, depends on what exactly you SELECTed (a single row, all rows in a table, a subset of rows, an aggregate on some/all rows, a join between several tables etc etc). But in general is not simple at all, and is always best to simply run the entire query again, discarding the previous result.
Think at Query Notifications as a means to actively invalidate caches, not as a mean to track changes.