MySQL query does not return any data
I need to retrieve data from a specific time period. The query works fine until I specify the time period. Is there something wrong with the way I specify time period? I know there are many entries within that time-frame.
开发者_如何学CThis query returns empty:
SELECT stop_times.stop_id, STR_TO_DATE(stop_times.arrival_time, '%H:%i:%s') as stopTime, routes.route_short_name, routes.route_long_name, trips.trip_headsign FROM trips
JOIN stop_times ON trips.trip_id = stop_times.trip_id
JOIN routes ON routes.route_id = trips.route_id
WHERE stop_times.stop_id = 5508
HAVING stopTime BETWEEN DATE_SUB(stopTime,INTERVAL 1 MINUTE) AND DATE_ADD(stopTime,INTERVAL 20 MINUTE);
Here is it's EXPLAIN:
+----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+
| 1 | SIMPLE | stop_times | ref | trip_id,stop_id | stop_id | 5 | const | 605 | Using where |
| 1 | SIMPLE | trips | eq_ref | PRIMARY,route_id | PRIMARY | 4 | wmata_gtfs.stop_times.trip_id | 1 | |
| 1 | SIMPLE | routes | eq_ref | PRIMARY | PRIMARY | 4 | wmata_gtfs.trips.route_id | 1 | |
+----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+
3 rows in set (0.00 sec)
The query works if I remove the HAVING clause (don't specify time range). Returns:
+---------+----------+------------------+-----------------+---------------+
| stop_id | stopTime | route_short_name | route_long_name | trip_headsign |
+---------+----------+------------------+-----------------+---------------+
| 5508 | 06:31:00 | "80" | "" | "FORT TOTTEN" |
| 5508 | 06:57:00 | "80" | "" | "FORT TOTTEN" |
| 5508 | 07:23:00 | "80" | "" | "FORT TOTTEN" |
| 5508 | 07:49:00 | "80" | "" | "FORT TOTTEN" |
| 5508 | 08:15:00 | "80" | "" | "FORT TOTTEN" |
| 5508 | 08:41:00 | "80" | "" | "FORT TOTTEN" |
| 5508 | 09:08:00 | "80" | "" | "FORT TOTTEN" |
I am using Google Transit format Data loaded into MySQL.
The query is supposed to provide stop times and bus routes for a given bus stop. For a bus stop, I am trying to get:
- Route Name
- Bus Name
- Bus Direction (headsign)
- Stop time The results should be limited only to buses times from 1 min ago to 20 min from now.
Please let me know if you could help.
UPDATE The problem was that I was comparing DATE to DATETIME as one answer said. I could not use DATE because my values had times but not dates. So my solution was to use Unix time:
SELECT stop_times.stop_id, stop_times.trip_id, UNIX_TIMESTAMP(CONCAT(DATE_FORMAT(NOW(),'%Y-%m-%d '), stop_times.arrival_time)) as stopTime, routes.route_short_name, routes.route_long_name, trips.trip_headsign FROM trips
JOIN stop_times ON trips.trip_id = stop_times.trip_id
JOIN routes ON routes.route_id = trips.route_id
WHERE stop_times.stop_id = 5508
HAVING stopTime > (UNIX_TIMESTAMP(NOW()) - 60) AND stopTime < (UNIX_TIMESTAMP(NOW()) + (60*20));
Stoptime is a time value, and DATE_ADD/SUB work with datetime fields. Ensure they are both the same type.
Try this instead:
SELECT * FROM
(SELECT stop_times.stop_id, STR_TO_DATE(stop_times.arrival_time, '%H:%i:%s') as stopTime, routes.route_short_name, routes.route_long_name, trips.trip_headsign FROM trips
JOIN stop_times ON trips.trip_id = stop_times.trip_id
JOIN routes ON routes.route_id = trips.route_id
WHERE stop_times.stop_id = 5508) AS qu_1
WHERE qu_1.stopTime BETWEEN DATE_SUB(qu_1.stopTime,INTERVAL 1 MINUTE) AND DATE_ADD(qu_1.stopTime,INTERVAL 20 MINUTE);
Have to warn you I haven't tested this but it does remove the need for the HAVING clause.
Don't work with the synthetic column stopTime other than as the output.
I think your query should be something like:
SELECT stop_times.stop_id, STR_TO_DATE(stop_times.arrival_time, '%H:%i:%s') as stopTime, routes.route_short_name, routes.route_long_name, trips.trip_headsign FROM trips
JOIN stop_times ON trips.trip_id = stop_times.trip_id
JOIN routes ON routes.route_id = trips.route_id
WHERE stop_times.stop_id = 5508
AND arrival_time BETWEEN <something> AND <something else>
The HAVING
clause you wrote should always return true, so I'm guessing that's not what you really had in mind.
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