Inner Join question

Question

I have assignment for sql query by asking list all products where designer of product lives in the same region as supplier of the product. However, I have no clue to solve it. Please assist.
Below are 4 tables I created:
CREATE Table REGION
RegCode          Varchar2 (8),
RegName          Varchar2 (40),
ShipDays          Number (2),
PRIMARY KEY     (RegCode)
CREATE Table SUPPLIER
SuppCode          Number (3),
SuppName          Varchar2 (50),
Rating          Varchar2 (1),
RegCode          Varchar2 (8),
PRIMARY KEY      (SuppCode),
FOREIGN KEY     (RegCode) REFERENCES REGION
CREATE table DESIGNER
FirstName          Varchar2 (30),
Surname          Varchar2 (30),
Email          Varchar2 (45),
Gender          Varchar2 (1),
RegCode          Varchar2 (8),
PRIMARY KEY     (FirstName, Surname),
FOREIGN KEY     (RegCode) REFERENCES REGION
CREATE table      PRODUCT
ProdCode          Varchar2 (3),
ProdName          Varchar2 (35),
SellingPrice     Varchar2 (4),
CostPrice          Varchar2 (4),
FirstName          Varchar2 (30),
Surname          Varchar2 (30),          
SuppCode          Number (3),
PRIMARY KEY     (ProdCode),
FOREIGN KEY      (FirstName,Surname) REFERENCES DESIGNER,
FOREIGN KEY      (SuppCode)     REFERENCES SUPPLIER
Thanks a ton,
Mandy

Answer 1

You won't need the region table at all, because the region code in supplier and designer will be enough for you to know that they are the same.
Do you know how to join tables at all?
Write your query by starting with products. Then join it to supplies using the value that is the primary key in supplier and a foreign key in products. Then, join to designer in the same manner. The only tricky thing about the second join is that you'l need two fields to complete the join. After that, you'll be ready to find records where the region code is the same.
Good luck! I hope this is enough to get you started...