Hi Winston McKenna,
Great question! Currently, there is no way to perform SQL queries in Insights.
However:
1. The filtering capability provides basic functionality for the time being.
2. We will be evolving our current filtering capabilities at both the dataset and card level as part of our 2018 road map. This will include increased flexibility in defining a custom where clause.
What specific type of queries are you looking to perform? This will help us as we evolve the filtering experience in Insights.
Thanks,
Nathan