We have a lot more ages now. How do we get the average age?

SELECT AVG(age) FROM people;SELECT age FROM people
WHERE age = AVG(age);SELECT AVG() FROM people
WHERE age;SELECT age FROM people
WHERE AVG();

Bingo. We have to pass a parameter to our function, so it knows what values to calculate with! Clauses don't accept aggregate functions.

Nope. We have to pass a parameter to our function, so it knows what values to calculate with! Clauses don't accept aggregate functions.