Looking up values from many tables based on value in each column - postgresql

Question

I have several tables containing key value pairs for differint fields in my database. I also have a table that that contains the keys of these differint tables that should be selected as the value for that key. However, I can't figure out how to select these values from the multiple tables?
The tables
CREATE TABLE CHARACTERS(
ID INTEGER PRIMARY KEY,
NAME VARCHAR(64)
);
CREATE TABLE MEDIA(
ID INTEGER PRIMARY KEY,
NAME VARCHAR(64)
);
CREATE TABLE EPISODES(
ID INTEGER PRIMARY KEY,
MEDIAID INTEGER,
NAME VARCHAR(64)
);
-- Selecting from this table
CREATE TABLE APPS(
ID INTEGER PRIMARY KEY,
CHARID INTEGER,
EPISODEID INTEGER,
MEDIAID INTEGER
);
I am selecting from the APPS table, and I want to replace the value of the *ID columns with the value of the name in the accomping table's NAME column. I want this done for each row in the APPS table. Like so...
CHARID -> CHARACTERS.NAME
EPISODEID -> EPISODES.NAME
MEDIAID -> MEDIA.NAME
I have tried to use joins, but they don't do it for each row in the APPS table. I have 18 rows in the APPS table, but I only get back way less than I have in the table or way more than I have in the table. So how can I make it do it for each row in the APPS table?

Answer 1

You do by JOINing the tables together and selecting the desired columns from the individual tables:
SELECT c.name AS character_name, e.name AS episode, m.name AS media
FROM apps a
LEFT JOIN episodes e ON e.id = a.episodeid
LEFT JOIN media m ON m.id = a.mediaid
LEFT JOIN characters c ON c.id = a.charid;
If you want to present the rows in a specific order, you can specify that too as a final clause in the SELECT statement. You can use any field from the included tables; that field is not necessarily part of the columns selected:
ORDER BY a.id -- order by apps.id
or
ORDER BY e.id, c.name -- order first by episode id, then by character name
etc