我从 mysql DB 中有一个很长的选择。它工作得非常快，直到我添加了这个 INNER JOIN。在我添加这个 INNER JOIN 选择时间之前是 2 秒，现在大约是 20 秒......
INNER JOIN
(SELECT
accomodation_id,
SUM(accomodation_rooms.rooms) AS total_rooms,
SUM(accomodation_rooms.beds * accomodation_rooms.rooms) AS total_persons
FROM accomodation_rooms
GROUP BY accomodation_id) accomodation_rooms
ON
accomodation_rooms.accomodation_id = accomodation.id
AND
accomodation_rooms.total_persons >= '".$persons."'
有人可以帮我一些更快的选择吗？
我已经通过删除额外的连接并将它们组合来修改您的查询，试试这个。
SELECT
accomodation.id,
accomodation.aid,
accomodation.title_en,
accomodation.title_url_en,
accomodation.address,
accomodation.zip,
accomodation.stars,
accomodation.picture,
accomodation.valid_from,
accomodation.valid_to,
accomodation.latitude,
accomodation.longitude,
MAX(info_date_add) AS max_info_date_add,
accomodation.city_id AS accomodation_city_id,
db_cities.id AS city_id,
db_cities.title_en AS city,
db_cities.title_url AS city_url,
db_countries.title_en AS country_title,
db_countries.title_url_en AS country_url,
accomodation_type.class AS accomodation_type_class,
accomodation_review_value_total.value AS review_total,
MIN(accomodation_price.price) AS price_from,
accomodation_rooms.total_persons,
(((acos(sin((db_cities.latitude * pi()/180)) * sin((accomodation.latitude * pi()/180)) + cos((db_cities.latitude * pi()/180)) * cos((accomodation.latitude * pi()/180)) * cos(((db_cities.longitude - accomodation.longitude) * pi()/180)))) * 180/pi()) * 60 * 1.1515 * 1.609344) as Calculation
FROM accomodation
LEFT JOIN db_cities ON db_cities.id = accomodation.city_id
LEFT JOIN db_countries ON db_countries.id = accomodation.country_id
LEFT JOIN accomodation_review_value_total ON accomodation_review_value_total.accomodation_aid = accomodation.aid
LEFT JOIN accomodation_price ON (accomodation_price.accomodation_aid = accomodation.aid AND accomodation_price.accomodation_price_type_id = '1' AND accomodation_price.accomodation_price_cat_id = '1')
INNER JOIN (SELECT
accomodation_id,
SUM(accomodation_rooms.rooms) AS total_rooms,
SUM(accomodation_rooms.beds * accomodation_rooms.rooms) AS total_persons
FROM accomodation_rooms
GROUP BY accomodation_id) accomodation_rooms
ON accomodation_rooms.accomodation_id = accomodation.id
AND accomodation_rooms.total_persons >= '4'
WHERE db_countries.title_url_en LIKE '%country%'
AND db_cities.title_url LIKE '%city%'
AND total_rooms >= '2'
AND db_cities.id = '2416'
GROUP BY accomodation.aid
HAVING Calculation < 20
ORDER BY CASE WHEN accomodation.valid_to >= NOW()
AND accomodation.valid_from <= NOW()THEN 0 WHEN NOW() > accomodation.valid_to
AND accomodation.valid_to != '0000-00-00'THEN 1 ELSE 2 END, review_total DESC, accomodation.title_en
LIMIT 10 OFFSET 0
编辑：
您仍然可以使用自己的加入方式
SELECT
accomodation.id,
accomodation.aid,
accomodation.title_en,
accomodation.title_url_en,
accomodation.address,
accomodation.zip,
accomodation.stars,
accomodation.picture,
accomodation.valid_from,
accomodation.valid_to,
accomodation.latitude,
accomodation.longitude,
MAX(info_date_add) AS max_info_date_add,
accomodation.city_id AS accomodation_city_id,
db_cities.id AS city_id,
db_cities.title_en AS city,
db_cities.title_url AS city_url,
db_countries.title_en AS country_title,
db_countries.title_url_en AS country_url,
accomodation_type.class AS accomodation_type_class,
accomodation_review_value_total.value AS review_total,
MIN(accomodation_price.price) AS price_from,
accomodation_rooms.total_persons,
SUM(IFNULL(accomodation_rooms.rooms,0,1)) AS total_rooms,
SUM(IFNULL(accomodation_rooms.beds * accomodation_rooms.rooms,0,1)) AS total_persons
FROM accomodation
LEFT JOIN db_cities
ON db_cities.id = accomodation.city_id
LEFT JOIN db_countries
ON (db_cities.id = accomodation.city_id
OR (((acos(sin((db_cities.latitude * pi()/180)) * sin((accomodation.latitude * pi()/180)) + cos((db_cities.latitude * pi()/180)) * cos((accomodation.latitude * pi()/180)) * cos(((db_cities.longitude - accomodation.longitude) * pi()/180)))) * 180/pi()) * 60 * 1.1515 * 1.609344) < '20')
LEFT JOIN accomodation_review_value_total
ON accomodation_review_value_total.accomodation_aid = accomodation.aid
LEFT JOIN accomodation_price
ON (accomodation_price.accomodation_aid = accomodation.aid
AND accomodation_price.accomodation_price_type_id = '1'
AND accomodation_price.accomodation_price_cat_id = '1')
LEFT JOIN accomodation_rooms
ON accomodation_rooms.accomodation_id = accomodation.id
WHERE db_countries.title_url_en LIKE '%country%'
AND db_cities.title_url LIKE '%city%'
AND total_rooms >= '2'
AND db_cities.id = '2416'
GROUP BY accomodation.aid
HAVING accomodation_rooms.total_persons >= '4'
ORDER BY CASE WHEN accomodation.valid_to >= NOW()
AND accomodation.valid_from <= NOW()THEN 0 WHEN NOW() > accomodation.valid_to
AND accomodation.valid_to != '0000-00-00'THEN 1 ELSE 2 END, review_total DESC, accomodation.title_en
LIMIT 10 OFFSET 0
这里的重要一点是您可以使用左连接而不是内连接，我认为这会更快。将 where 条件放在 HAVAING 子句中。另请注意，我在选择时应用了 IF 条件，因此如果出现 null，则总和为 0，否则为 1。
SELECT
accomodation.id,
accomodation.aid,
accomodation.title_en,
accomodation.title_url_en,
accomodation.address,
accomodation.zip,
accomodation.stars,
accomodation.picture,
accomodation.valid_from,
accomodation.valid_to,
accomodation.latitude,
accomodation.longitude,
accomodation.city_id AS accomodation_city_id,
db_cities.id AS city_id,
db_cities.title_en AS city,
db_cities.title_url AS city_url,
db_countries.title_en AS country_title,
db_countries.title_url_en AS country_url,
accomodation_type.class AS accomodation_type_class,
accomodation_review_value_total.value AS review_total,
MIN(accomodation_price.price) AS price_from,
accomodation_rooms.total_persons
FROM
(SELECT aid, MAX(info_date_add) AS max_info_date_add FROM accomodation GROUP BY aid) accomodation_max
INNER JOIN accomodation
ON
accomodation_max.aid = accomodation.aid AND
accomodation_max.max_info_date_add = accomodation.info_date_add
LEFT JOIN db_cities
ON
( db_cities.id = accomodation.city_id OR (((acos(sin((db_cities.latitude*pi()/180)) * sin((accomodation.latitude*pi()/180)) + cos((db_cities.latitude*pi()/180)) * cos((accomodation.latitude*pi()/180)) * cos(((db_cities.longitude - accomodation.longitude)*pi()/180))))*180/pi())*60*1.1515*1.609344) < '20')
JOIN db_countries
ON db_countries.id = accomodation.country_id
LEFT JOIN accomodation_review_value_total
ON accomodation_review_value_total.accomodation_aid = accomodation.aid
LEFT JOIN accomodation_type_value
ON accomodation_type_value.accomodation_id = accomodation.id
LEFT JOIN accomodation_type
ON accomodation_type.id = accomodation_type_value.accomodation_type_id
LEFT JOIN accomodation_price
ON
( accomodation_price.accomodation_aid = accomodation.aid AND
accomodation_price.accomodation_price_type_id = '1' AND
accomodation_price.accomodation_price_cat_id = '1' )
LEFT JOIN accomodation_season
ON
( accomodation_season.accomodation_aid = accomodation.aid AND
accomodation_season.id = accomodation_price.accomodation_season_id AND
( '2013-09-25' >= accomodation_season.start_date AND
accomodation_season.end_date >= '2013-09-25' OR '2013-09-26' >= accomodation_season.start_date AND
accomodation_season.end_date >= '2013-09-26' ) )
INNER JOIN
(SELECT accomodation_id, SUM(accomodation_rooms.rooms) AS total_rooms,
SUM(accomodation_rooms.beds * accomodation_rooms.rooms) AS total_persons
FROM accomodation_rooms
GROUP BY accomodation_id) accomodation_rooms
ON
accomodation_rooms.accomodation_id = accomodation.id AND
accomodation_rooms.total_persons >= '4'
WHERE
db_countries.title_url_en LIKE '%country%' AND
db_cities.title_url LIKE '%city%' AND
total_rooms >= '2' AND
db_cities.id = '2416'
GROUP BY accomodation.aid
ORDER BY CASE
WHEN
accomodation.valid_to>=NOW() AND
accomodation.valid_from<=NOW() THEN 0
WHEN
NOW()>accomodation.valid_to AND
accomodation.valid_to!='0000-00-00' THEN 1 ELSE 2 END,
review_total DESC, accomodation.title_en LIMIT 10 OFFSET 0