Tricky~20min
The Vaccine Given Twice in One Day
5 pets got the SAME vaccine twice on the same day at two different clinic locations in the chain — a duplicate administration nobody caught because the two locations don't share real-time records. 8 other pets also have two vaccine records the same day, but they're two different vaccine types — a normal combo visit.
Tables you'll query
petsvaccine_records
What you'll learn
Aggregations & GROUP BY