Mysql select from inner select with join - mysql

Question

Can I do something like this ? Bassically I user inner select to select lowest date that is bigger than NOW(), for example 9.4.2014 would mathc this, for each event ids. And now I would like to return this, here is the code :
SELECT id_event , event_title, event_details, dates.event_date, id_show, id_category, distance FROM(
SELECT event.id_event id_event, event_title, event_details, min(event_date_time) event_date_time, event_showtime.id_show , event_category.id_category id_category, ( 6371 * ACOS( COS( RADIANS( '49.20513921227407' ) ) * COS( RADIANS( event_showtime.latitude ) ) * COS( RADIANS( event_showtime.longitude ) - RADIANS( '18.762441839599678' ) ) + SIN( RADIANS( '49.20513921227407' ) ) * SIN( RADIANS( event_showtime.latitude ) ) ) ) AS distance
FROM event
JOIN event_showtime ON event.id_event = event_showtime.id_event
JOIN event_category ON event.id_category = event_category.id_category
JOIN ( SELECT id_event, min(event_date_time) as event_date_time FROM event_showtime
WHERE event_date_time > NOW()
GROUP BY id_event ) AS dates ON event.id_event = dates.id_event
WHERE event_date_time > NOW()
GROUP BY event.id_event
HAVING distance < '5'
ORDER BY distance
LIMIT 0 , 20
)t
Here is the SQLfiddle http://www.sqlfiddle.com/#!2/6545ab/51 with 3 tables :)
How could I access those inner details in the top select ?

Answer 1

You need to give the table aliases to your columns if there are multiple columns that have same names
SELECT
es.id_show,
e.id_event ,
e.event_title,
e.event_details,
d.event_date_time,
ec.id_category,
( 6371 * ACOS( COS( RADIANS( '49.20513921227407' ) ) * COS( RADIANS( es.latitude ) ) * COS( RADIANS( es.longitude ) - RADIANS( '18.762441839599678' ) ) + SIN( RADIANS( '49.20513921227407' ) ) * SIN( RADIANS( es.latitude ) ) ) ) AS distance
FROM event e
JOIN event_showtime es ON e.id_event = es.id_event
JOIN event_category ec ON e.id_category = ec.id_category
JOIN ( SELECT id_event,
min(event_date_time) as event_date_time
FROM event_showtime
WHERE event_date_time > NOW()
GROUP BY id_event ) AS d
ON (es.id_event = d.id_event AND es.event_date_time =d.event_date_time)
WHERE d.event_date_time > NOW()
GROUP BY e.id_event
-- HAVING distance < '5'
ORDER BY distance
LIMIT 0 , 20
Here is the simplified version of your query you are using HAVING clause to check the distance should be less than 5 but for second event the distance is 112.773868864733 in my query i have commented the having clause just to show your the results,second thing you asked for the nearest date to NOW() but not include past dates so in your provided sample data set for event_showtime
`id_show`, `id_event`, `latitude`, `longitude`, `event_date_time`
(1, 1, 49.2016762922894, 18.7615620750428, '2014-03-31 16:13:17'),
(2, 1, 49.2016762922894, 18.7615620750428, '2014-04-01 20:00:00'),
(3, 2, 49.2113914818564, 18.7520992416382, '2014-03-31 15:00:00'),
(4, 2, 49.0545135142313, 20.2952223676682, '2014-04-16 11:00:00'),
(5, 2, 49.2113914818564, 18.7520992416382, '2014-04-23 11:00:00'),
(6, 2, 49.0545135142313, 20.2952223676682, '2014-04-30 11:00:00'),
(7, 2, 49.2016762922894, 18.7615620750428, '2014-04-29 12:00:00'),
(8, 1, 49.2016762922894, 18.7615620750428, '2014-04-24 12:00:00');
For event id 1 there are 3 datetimes 2014-03-31 16:13:17 ,2014-04-01 20:00:00,2014-04-24 12:00:00 the date 2014-04-24 12:00:00 is the nearest one for event id 2 the date 2014-04-16 11:00:00 is the nearest one not 23rd one ,third thing you asked in comments that id_show is wrong for this your last join from subquery needs another condition with event_date_time to be joined to get the exact id you need
Hope it makes sense
Fiddle Demo
For your specific requirement to select nearest dates with distance limitation you can do so
SELECT t.* FROM (
SELECT
es.id_show,
e.id_event,
e.event_title,
e.event_details,
MIN(es.event_date_time) event_date_time,
ec.id_category,
es.distance
FROM
event e
JOIN event_category ec
ON e.id_category = ec.id_category
JOIN
(SELECT
`id_show`,
`id_event`,
`latitude`,
`longitude`,
event_date_time,
(
6371 * ACOS(
COS(RADIANS('49.20513921227407')) * COS(RADIANS(event_showtime.latitude)) * COS(
RADIANS(event_showtime.longitude) - RADIANS('18.762441839599678')
) + SIN(RADIANS('49.20513921227407')) * SIN(RADIANS(event_showtime.latitude))
)
) AS distance
FROM
event_showtime
WHERE `event_date_time` > NOW()
HAVING distance < 5) es
ON (e.id_event = es.id_event)
GROUP BY e.id_event
) t
JOIN `event_showtime` es USING(id_event,event_date_time)
ORDER BY t.distance
LIMIT 0, 20
Fiddle Demo