I'm just getting started on an intro to databases course and have a question about writing relational algebra expressions.
Person ( name, age, gender ) Frequents ( name, pizzeria ) Eats ( name, pizza ) Serves ( pizzeria, pizza, price )
I have a practice question like such: Find all pizzerias that serve at least one pizza that Amy eats for less than $10.00.
My answer is: πpizzeria (σname = 'Amy' ^ price < $10 (Person ⨝ Serves))
A correct answer is: πpizzeria (σname = 'Amy' (Eats) ⨝ σprice < $10 (Serves))
I would like to know if these two are equivalent to each other, and if not, why not?