Paul Lambert wrote:
Colin Wetherbee wrote:
I would like to construct a query on the flight table that returns the
names of both the departure port and the arrival port.
The following query shows how I would get just the departure port.
js=# SELECT departure_date, jsports.code AS departure_code FROM
jsjourneys JOIN jsports ON jsjourneys.departure_port = jsports.id LIMIT
4;
Try joining twice, something like:
SELECT departure_date,
dp.code AS departure_code,
ap.code AS arrival_code
FROM jsjourneys
JOIN jsports dp ON jsjourneys.departure_port = jsports.id
JOIN jsports ap ON jsjourneys.arrival_port=jsports.id
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TIP 6: explain analyze is your friend
Ah, I didn't realize you could alias tables inside the JOIN. Excellent.
It works. :)
js=# SELECT departure_date, dp.code AS departure_code, ap.code AS
arrival_code FROM jsjourneys JOIN jsports dp ON
jsjourneys.departure_port = dp.id JOIN jsports ap ON
jsjourneys.arrival_port = ap.id LIMIT 4;
departure_date | departure_code | arrival_code
----------------+----------------+--------------
2006-11-19 | BHM | ATL
2006-11-16 | PIT | ATL
2006-11-16 | ATL | BHM
2006-10-26 | PIT | BOS
(4 rows)
For archive completeness, note the query is joined relative to dp.id and
ap.id, rather than jsports.id.
Thanks for your help!
Colin
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