Selecting from a table that contains ALL of another table - sql

Question

Let's say I have three tables:
Employees:
PID NAME WAGE
---------- -------------------- ----------
10234 Able 8
11567 Baker 9
3289 George 10
88331 Alice 11
Employee_made:
PID SID QUANTITY HOURS
---------- ---------- ---------- ----------
10234 11 24 3
10234 12 6 1
10234 13 24 1
10234 21 6 1
10234 23 4 1
10234 31 48 6
11567 23 4 1
11567 31 1 1
88331 11 6 1
Sandwich:
SID PRICE NAME
---------- ---------- ------------------------------
12 2 hamburger on wheat
13 2 cheese burger
21 1.75 fish burger on rye
23 1.75 fish burger on wheat
31 3 veggie burger on wheat
11 2 hamburger on rye
I need to list all the employees who have made ALL the different sandwiches, and display their names and PID. What I've gotten so far is:
Select E.name, E.pid
From employees E, employee_made EM, sandwich S
Where E.pid = EM.pid
Which tells me the matching PIDs from the employees and employee_made table. Where I'm not sure to go is how to display the employees who have made ALL the sandwiches, so matching not any SID to the employee_made table, but ALL of them.

Answer 1

First, never use commas in the FROM clause. Always use proper, explicit JOIN syntax.
You can approach this by counting the number of sandwiches mades by employees and then comparing to the total count of sandwiches:
select em.pid
from employee_made em
group by em.pid
having count(distinct em.sid) = (select count(*) from sandwich);
This gives the pid of the employee. I'll let you figure out how to bring in the employee name (hint: in, exists, and join could all be used).