How do you ensure your SQL queries (either raw or ORM generated) retrieve the correct data? A lot of business apps are mostly SQL with a thin layer of glue to

How do you ensure your SQL queries (either raw or ORM generated) retrieve the correct data? A lot of business apps are mostly SQL with a thin layer of glue to integrate everything. I think it depends on what the app does--is it data manipulation heavy (lots of complex relations) or is it compute/algorithm heavy (simpler relations, lots of logic).