SQL - Insert valid data based on predefined values - sql

Question

I have two tables city and suburb. Postgresql code:
CREATE TABLE city
(
id uuid PRIMARY KEY,
name character varying NOT NULL,
CONSTRAINT city_id_key UNIQUE (id),
CONSTRAINT city_name_key UNIQUE (name)
)
CREATE TABLE suburb
(
id uuid PRIMARY KEY,
city_id uuid NOT NULL,
name character varying NOT NULL,
CONSTRAINT fk_suburb_city FOREIGN KEY (city_id) REFERENCES city (id),
CONSTRAINT suburb_id_key UNIQUE (id),
CONSTRAINT suburb_name_key UNIQUE (name)
)
I want to create a table called address for storing city + suburb pairs. Here is the DDL for address table:
CREATE TABLE address
(
id uuid NOT NULL,
city_name character varying NOT NULL,
suburb_name character varying NOT NULL
)
I want to make sure that only redundant copies of information is inserted into address. Here is an example:
I want to allow inserting into address all the city_name suburb_name pairs:
SELECT c.name AS city_name, s.name AS suburb_name
FROM city c, suburb s
WHERE c.id = s.city_id
Result:
A - B
A - C
X - Y
For the data above I want to allow all the pairs:
A - B
A - C
X - Y
But if someone wants to insert A - Y pair into address, I want the DBMS to raise an error/exception.
Questions:
Does it make sense to check a constraint like this?
If it is a valid idea, what is the best solution for this? Trigger, stored procedure, some kind of constraint?
I prefer DBSM independent solutions. I'm more interested in the basic idea of the suggested solution not in a postgresql specific solution.
Reflecting to #Yuri G's answer: I don't want any join when I read form address. I want to store real values in it not ids. Slow insert into address is not problem. Fast read is important for me. Change in city or suburb table is not a problem after insertion in address. So no need for update in address table. I just want to make sure that the data I insert into address is a valid city - suburb pair (according to city and suburb tables).
My plan is to upload city and suburb tables with lots of data and use them for validating insertions in address table. I don't want to allow my users to insert into address for example: "New York - Fatima bint Mubarak St" because Fatima bint Mubarak St. is in Abu Dhabi.
Thank you for the answers.

Answer 1

Let the software on the client side operate the record identifiers for City & Suburb, not their values.
And do so on the server side too:
CREATE TABLE address
(
id uuid NOT NULL,
city_id character varying NOT NULL,
suburb_id character varying NOT NULL,
CONSTRAINT fk_city FOREIGN KEY (city_id) REFERENCES city (id),
CONSTRAINT fk_suburb FOREIGN KEY (suburb_id) REFERENCES suburb (id),
)
Of course, you'll need 2 lookup operations prior to insert, basically two selects by name of the city/suburb, to retrieve these IDs (or deny operation).
Though this way you'd be keeping data integrity most simple & efficient way, I believe.