You know I have the way to Cache the data I've got from the SQL Server over data caching. In addition I can output cache web user controls.
Whats about a web user control contains data from a SQL database? Does it make sense to cache the data and also cache the control?
What is the best solution for the combination of these two components?
Yes. this is a newbie question.
If you cache the control, then you don't need to cache the underlying data. Optimal caching, as always, depends on your application.
Here are some general guidelines:
Use data caching for complex, CPU/Memory intensive queries, for data that is used very often on different pages/controls.
Use output caching for controls that appear often. Output caching also tends to be simpler to implement compared to data caching with requires more thought concerning threading/locking, etc.