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主页 / dba / 问题 / 250577
Accepted
arilwan
arilwan
Asked: 2019-10-09 10:59:33 +0800 CST2019-10-09 10:59:33 +0800 CST 2019-10-09 10:59:33 +0800 CST

使用 WITH 子句创建两个子查询

  • 772

我正在努力处理涉及两个使用此处WITH描述的子句的子查询的非常复杂的查询。

但在我看来,我不能在主查询中使用一个子查询。我这里是我的查询语句:

WITH trip_labelled AS
(
    SELECT DISTINCT ON (trips_1.trip_id) trips_1.trip_id,
            sum(segments.length::double precision) AS segments_length,
            sum(travelmode_profile.foot * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS foot,
            sum(travelmode_profile.bike * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS bike,
            sum(travelmode_profile.car * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS car,
            sum(travelmode_profile.bus * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS bus,
            sum(travelmode_profile.metro * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS metro
           FROM trips trips_1
             JOIN segments ON segments.session_id = ANY (trips_1.session_ids)
             JOIN travelmode_profile USING (session_id, segment_id)
             LEFT JOIN session USING (session_id)
             LEFT JOIN ( SELECT DISTINCT ON (session_1.user_id) session_1.user_id,
                    response.response AS role
                   FROM session session_1
                     LEFT JOIN response USING (session_id)
                  WHERE response.question_id = 24) demography USING (user_id)
          WHERE segments.movement = true
          GROUP BY trips_1.trip_id
),
   trip_mode AS
(   SELECT trips.trip_id AS trip_id,
       trips.seconds_start,
       trips.seconds_end,
       trips.distance,
         CASE
            WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.car THEN 'car'::text
            WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.bike THEN 'bike'::text
            WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.bus THEN 'bus'::text
            WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.metro THEN 'metro'::text
            WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.foot THEN 'foot'::text
            ELSE NULL::text
        END AS travel_mode
   FROM trips
     JOIN trip_labelled USING (trip_id)
  )
  SELECT  session_id, 
         COALESCE(gps.gpstime, gslocation.gpstime) AS gpstime,
         COALESCE(gps.lat, gslocation.lat) AS lat,
        COALESCE(gps.lon, gslocation.lon) AS lon,
        COALESCE(gps.alt, gslocation.alt) AS alt,
        COALESCE(gps.speed, gslocation.speed) AS speed,
        COALESCE(gps.acc, gslocation.acc) AS acc
        trip_mode.travel_mode
FROM raw_data.gslocation
FULL JOIN raw_data.gps
    USING (session_id, seconds, millis);

错误:

ERROR:  syntax error at or near "trip_mode"
LINE 53:   trip_mode.travel_mode

我不能在主查询中使用travel_mode或trip_mode.travel_mode来自第二个子trip_mode查询。但致力于注释掉travel_mode/trip_mode.travel_mode。我哪里出错了?

postgresql
  • 2 2 个回答
  • 61 Views

2 个回答

  • Voted
  1. Best Answer
    Laurenz Albe
    2019-10-09T13:46:28+08:002019-10-09T13:46:28+08:00

    您的查询有两个问题:

    1. 你之前少了一个逗号trip_mode.travel_mode。

    2. 如果要在主查询中引用 CTE,则必须将它们添加到FROM子句中。

    • 2
  2. Florin Irion
    2019-10-09T13:00:43+08:002019-10-09T13:00:43+08:00

    您需要在 case 语句周围使用括号。

    尝试这个:

    WITH trip_labelled AS
    (
        SELECT DISTINCT ON (trips_1.trip_id) trips_1.trip_id,
                sum(segments.length::double precision) AS segments_length,
                sum(travelmode_profile.foot * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS foot,
                sum(travelmode_profile.bike * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS bike,
                sum(travelmode_profile.car * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS car,
                sum(travelmode_profile.bus * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS bus,
                sum(travelmode_profile.metro * segments.length)::real / GREATEST(sum(segments.length), 1::real) AS metro
               FROM trips trips_1
                 JOIN segments ON segments.session_id = ANY (trips_1.session_ids)
                 JOIN travelmode_profile USING (session_id, segment_id)
                 LEFT JOIN session USING (session_id)
                 LEFT JOIN ( SELECT DISTINCT ON (session_1.user_id) session_1.user_id,
                        response.response AS role
                       FROM session session_1
                         LEFT JOIN response USING (session_id)
                      WHERE response.question_id = 24) demography USING (user_id)
              WHERE segments.movement = true
              GROUP BY trips_1.trip_id
    ),
       trip_mode AS
    (   SELECT trips.trip_id AS trip_id,
           trips.seconds_start,
           trips.seconds_end,
           trips.distance,
             (CASE
                WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.car THEN 'car'::text
                WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.bike THEN 'bike'::text
                WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.bus THEN 'bus'::text
                WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.metro THEN 'metro'::text
                WHEN GREATEST(trip_labelled.car, trip_labelled.bike, trip_labelled.bus, trip_labelled.metro, trip_labelled.foot) = trip_labelled.foot THEN 'foot'::text
                ELSE NULL::text
            END) AS travel_mode
       FROM trips
         JOIN trip_labelled USING (trip_id)
      )
      SELECT  session_id,
             COALESCE(gps.gpstime, gslocation.gpstime) AS gpstime,
             COALESCE(gps.lat, gslocation.lat) AS lat,
            COALESCE(gps.lon, gslocation.lon) AS lon,
            COALESCE(gps.alt, gslocation.alt) AS alt,
            COALESCE(gps.speed, gslocation.speed) AS speed,
            COALESCE(gps.acc, gslocation.acc) AS acca,
            trip_mode.travel_mode
    FROM raw_data.gslocation
    FULL JOIN raw_data.gps
        USING (session_id, seconds, millis);
    
    • -1

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