RA query to find all pizzerias that serve every pizza eaten by people over 30. https://stanford.io/2GkWfPx

gistfile1.txt

/* Flawed as assumes 2 pizzas eaten by those over 30 should be free from this */


(\project_{pizzeria}(
    \rename_{pizza}(                                    // renames as Pizza so they can then be joined with Serves to collect the Pizzeria
        \project_{pizza1}(                              // take only first pizza
            \select_{pizza1 < pizza2}((                 // gives one column for pizza 1 and a collumn for pizza 2
                \rename_{pizza1}(                       // need to rename to be able to do cross product
                    \project_{pizza}((
                        \project_{pizza}((              // Select pizzas from table with pizzas eaten by people over 30
                            \select_{age > 30}Person)
                            \join Eats
                        )
                    )
                        \join(
                            \project_{pizza, pizzeria}Serves
                        )
                    )
                )
            )
            \cross(                                   // cross product to take only the pizzas eaten by those over 30
                \rename_{pizza2}(
                    \project_{pizza}((
                        \project_{pizza}((
                            \select_{age > 30}Person) 
                                \join Eats
                        )
                    )
                        \join(
                            \project_{pizza, pizzeria}Serves
                        )
                    )
                    )
            ))
        )
    )
    \join 
        Serves
))
\intersect                                          // find intersect of pizzerias serving pizza 1 and pizza 2
(\project_{pizzeria}(
    \rename_{pizza}(
        \project_{pizza2}(                         // take only second pizza
            \select_{pizza1 < pizza2}((
                \rename_{pizza1}(
                    \project_{pizza}((
                        \project_{pizza}((
                            \select_{age > 30}Person)
                            \join Eats
                        )
                    )
                        \join(
                            \project_{pizza, pizzeria}Serves)
                    )
                )
            )
                \cross(\rename_{pizza2}(
                    \project_{pizza}((
                        \project_{pizza}((
                            \select_{age > 30}Person)
                            \join Eats
                        )
                    )
                        \join (
                            \project_{pizza, pizzeria}Serves)
                    )
                ))
            )
        )
    )
    \join Serves
))


/* version with spaces taken out to fit under 1000 characters */
(\project_{pizzeria}(\rename_{pizza}(\project_{pizza1}(\select_{pizza1 < pizza2}((\rename_{pizza1}(\project_{pizza}((\project_{pizza}((\select_{age > 30}Person)\join Eats))\join(\project_{pizza, pizzeria}Serves))))\cross(\rename_{pizza2}(\project_{pizza}((\project_{pizza}((\select_{age > 30}Person) \join Eats))\join(\project_{pizza, pizzeria}Serves)))))))\join Serves))
\intersect
(\project_{pizzeria}(\rename_{pizza}(\project_{pizza2}(\select_{pizza1 < pizza2}((\rename_{pizza1}(\project_{pizza}((\project_{pizza}((\select_{age > 30}Person)\join Eats))\join(\project_{pizza, pizzeria}Serves))))\cross(\rename_{pizza2}(\project_{pizza}((\project_{pizza}((\select_{age > 30}Person)\join Eats))\join (\project_{pizza, pizzeria}Serves)))))))\join Serves))