====== Nützliches SQL ======

===== doppelter join =====

Wir hätten gerne aus einer Tabelle nur die Zeile wo climate.date max ist, gruppiert nach climate.stations und wollen noch stations.name anzeigen.

<code sql>
SELECT stations.lat AS lat, stations.lon AS lon, stations.name AS name, climate.tmk AS tmk
FROM climate
INNER JOIN (
    SELECT climate.station, MAX(climate.date) AS date
    FROM climate
    GROUP BY climate.station
) AS c
ON climate.station = c.station AND climate.date = c.date
INNER JOIN stations
ON climate.station = stations.id
ORDER BY climate.station;
</code>