MySQL find results based on two different values of the same column - mysql

Question

list employees names (Ename) who have both 49008 zip code customers and 49009 zip code customers.
I am struggling to answer the above query based on the above tables.
If the names match between tables assume constraint.
I can filter down to name and zip easily by left joins and group by but struggle after that, I don't know the proper where or having statement. I am assuming it could be done better by a sub query but not sure. Ideally, a single query.
Please and thank you.
1) Create and insert statements for example data:
Create table Employees (EM_Eno INT NOT NULL, EM_Ename VARCHAR(50), EM_Hire_Date DATE, PRIMARY KEY(EM_Eno));
Create table Customers (Customers_Cno INT NOT NULL, Customers_Cname VARCHAR(50), Customers_Street VARCHAR(50), Customers_Zip INT, Customers_Phone INT, primary key(Customers_Cno));
Create table Orders (Orders_Ono INT NOT NULL, Orders_Cno INT, Orders_Eno INT, Orders_Received DATE, Orders_Shipped DATE, primary key(Orders_Ono));
insert into Orders values
( 1,301,501,20161010,20161011);
( 2,302,501,20161011,20161012);
( 3,303,502,20161110,20161111);
( 4,304,502,20161110,20161112);
( 5,305,502,20161110,20161113);
( 6,306,503,20161112,20161114);
( 7,307,501,20161112,20161113);
( 8,308,503,20161112,20161115);
( 9,309,503,20161115,20161120);
(10,300,501,20161112,20161113);
insert into Customers values
(300,'Bryan','100 street',49009,1234567890),
(301,'Ryan','101 street',49008,1234567890),
(302,'Nick','102 street',49009,1234567890),
(303,'Nicholas','103 street',49009,1234567890),
(304,'Alexa','104 street',49009,1234567890),
(305,'Tori','105 street',49008,1234567890),
(306,'Scarlet','106 street',49008,1234567890),
(307,'Heather','100 street',49009,1234567890),
(308,'Amanda','107 street',49008,1234567890),
(309,'James','108 street',49008,1234567890);
insert into Employees values
(501,'Robert',20041010),
(502,'Sam',20050110),
(503,'Brandy',20050710);
2) Ideal end result is answering the query "list employees (names) who have both 49008-zipcode customers and 49009-zipcode customers."
3) Best Attempt thus far:
select Employees.EM_Ename
, Customers.Customers_Zip
from Employees
left
join Orders
on Employees.EM_Eno = Orders.Orders_Eno
left
join Customers
on Orders.Orders_Cno = Customers.Customers_Cno
group
by Employees.EM_Ename
, Customers.Customers_Zip;

Answer 1

The table names are altered slightly in the rextest, because other tables already exist there with the same name...
SELECT e.*
FROM tbl_employees e
JOIN tbl_orders o
ON o.orders_eno = e.em_eno
JOIN tbl_customers c
ON c.Customers_Cno = o.Orders_Cno
WHERE c.Customers_Zip IN(49008,49009)
GROUP
BY e.em_eno
HAVING COUNT(DISTINCT customers_zip) = 2;
http://rextester.com/HCNLU51847

Answer 2

This should be what you want:
select Min(e.Ename)
from #Employees e
join #Orders o on o.Eno = e.Eno
join #Customers c on c.Cno = o.Cno
join #Orders o2 on o2.Eno = e.Eno
join #Customers c2 on c2.Cno = o2.Cno
where o.Ono !=o2.Ono--c.Cno != c2.Cno and
and c.Zip = 49008 and c2.Zip = 49009
group by e.Ename,c.Zip
order by e.Ename
As you can see if you wanted more than those two the self joins become longer.