Join Alias ​​Columns SQL

Der Alias ​​"Datum" ist von dort aus nicht zu sehen.

Sie können einige Tabellen nach WITH verwenden, daher rate ich Ihnen, die zweite Auswahl dorthin zu verschieben.

Ich bin mir bei der Tabellenstruktur von weather.meso nicht ganz sicher, aber basierend auf Ihrer Abfrage sollte dies funktionieren:

WITH
    forecast_prep AS (
        SELECT
              date_trunc('day', foretime) :: DATE AS Foredate,
              extract(HOUR FROM foretime) + 1     AS foreHE,
              lat,
              lon,
              max(windspeed) as windspeed,
              max(as_of)                          AS as_of
        FROM weather.forecast
        WHERE date_trunc('day', foretime) :: DATE - as_of >= INTERVAL '16 hours'
        GROUP BY Foredate, foreHE, lat, lon
   ),
   tmp AS (
      SELECT
        meso.station,
        meso.lat,
        meso.lon,
        meso.timestmp,
        date_trunc('day', meso.timestmp) :: DATE  AS Date,
        extract(HOUR FROM meso.timestmp) + 1      AS HE,
        CAST(AVG(meso.windspd) AS NUMERIC(19, 2)) AS Actual
      FROM weather.meso
      GROUP BY station, lat, lon, timestmp, Date, HE
   )
SELECT 
    tmp.station, tmp.Date, tmp.HE, tmp.Actual, forecast_prep.windspeed, forecast_prep.as_of
FROM tmp
INNER JOIN forecast_prep ON (
    tmp.lat = forecast_prep.lat 
    AND tmp.lon = forecast_prep.lon 
    AND tmp.Date = forecast_prep.Foredate
    AND tmp.HE = forecast_prep.foreHE
)
WHERE 
    (tmp.timestmp BETWEEN '2016-02-01' AND '2016-02-02') 
    AND (tmp.station = 'KSBN')
GROUP BY 
    tmp.station, tmp.Date, tmp.HE, forecast_prep.windspeed, forecast_prep.as_of, tmp.Actual
ORDER BY tmp.Date, tmp.HE ASC;

Wie im ersten Beispiel hier https://www.postgresql.org/docs/8.4/static/queries-with.html