SQL查詢花費時間過長（LEFT OUTER JOIN）

Question

我一直在測試SQL查詢以尋求從列'車隊'，'行程'，'預訂'，'代理商'和'人員'獲取數據的查詢。

問題是這個查詢花了很長時間（2分鐘）才能完成。 我嘗試使用'WHERE'和/或'INNER JOIN'，查詢時間縮短到幾毫秒，但它並沒有給我所有我想要的結果。例如，「旅行」中有一些條目沒有「預訂」關聯或某些「預訂」條目沒有「人員」關聯。這就是爲什麼我需要使用LEFT OUTER JOIN，但這使得查詢非常緩慢。

我相信我在這個語法中有一些效率問題，但我無法弄清楚它是什麼。

我想要的結果是這樣的：

bid  tid  tstatus timestamp start end gname pname fname  blockedtrips tcreator bcreator baname taname 
NULL 2736 1   1468022400 540  720 NULL NULL Little Boy 1    9   NULL  NULL Conscience Dauphin 
NULL 2737 1   1468022400 540  720 NULL NULL Moby Dick 1    9   NULL  NULL Conscience Dauphin 

我的查詢如下：

SELECT 
bookings.id AS bid, trips.id AS tid, trips.id_status AS tstatus, 
trips.timestamp, trips.start, trips.end, bookings.groupname AS gname, 
persons.name AS pname, fleet.name AS fname, trips.blockedtrips AS blockedtrips, 
trips.id_creator AS tcreator, bookings.id_creator AS bcreator, 
(SELECT name FROM agencies WHERE deleted=false AND id=bookings.id_agency) AS baname, 
(SELECT name FROM agencies WHERE deleted=false AND id=trips.id_agency) AS taname 
FROM 
trips OUTER LEFT JOIN fleet ON fleet.id = trips.id_fleet AND fleet.deleted=false AND trips.deleted=false 
LEFT OUTER JOIN bookings ON trips.id = bookings.id_trip AND bookings.deleted=false 
LEFT OUTER JOIN persons ON bookings.id = persons.id_booking AND persons.deleted=false 
    AND ( 
    (SELECT name FROM agencies WHERE deleted=false AND id=bookings.id_agency) LIKE '%conscience%' 
    OR (SELECT name FROM agencies WHERE deleted=false AND id=trips.id_agency) LIKE '%conscience%' 
    OR bookings.groupname LIKE '%conscience%' 
    OR persons.name LIKE '%conscience%' 
    OR fleet.name LIKE '%conscience%' 
) 
    ORDER BY trips.timestamp 
    DESC LIMIT 0,100 

查詢而更新：

SELECT 
    bookings.id AS bid, trips.id AS tid, trips.id_status AS tstatus, 
    trips.timestamp, trips.start, trips.end, bookings.groupname AS gname, 
    persons.name AS pname, fleet.name AS fname, trips.blockedtrips AS blockedtrips, 
    trips.id_creator AS tcreator, bookings.id_creator AS bcreator, 
    bagency.name AS baname, tagency.name AS taname 
FROM fleet 
    LEFT JOIN trips ON fleet.id = trips.id_fleet AND fleet.deleted=false AND trips.deleted=false 
    LEFT JOIN agencies AS tagency ON tagency.id = trips.id_agency AND tagency.deleted=false 
    LEFT JOIN bookings ON trips.id = bookings.id_trip AND bookings.deleted=false 
    LEFT JOIN agencies AS bagency ON bagency.id = bookings.id_agency AND bagency.deleted=false 
    LEFT JOIN persons ON bookings.id = persons.id_booking AND persons.deleted=false 
WHERE 
    bagency.name LIKE '%conscience%' 
    OR tagency.name LIKE '%conscience%' 
    OR bookings.groupname LIKE '%conscience%' 
    OR persons.name LIKE '%conscience%' 
    OR fleet.name LIKE '%conscience%' 
ORDER BY trips.timestamp DESC 
LIMIT 0,100 

Answer 1

，你可以連接表與agencies而不是使用多個子查詢，這應該給你相同的結果，試試它希望它是他lpful：

SELECT 
bookings.id AS bid, trips.id AS tid, trips.id_status AS tstatus, 
trips.timestamp, trips.start, trips.end, bookings.groupname AS gname, 
persons.name AS pname, fleet.name AS fname, trips.blockedtrips AS blockedtrips, 
trips.id_creator AS tcreator, bookings.id_creator AS bcreator, 
ag1.name AS baname, 
ag2.name AS taname 
FROM 
trips OUTER LEFT JOIN fleet ON fleet.id = trips.id_fleet AND fleet.deleted=false AND trips.deleted=false 
LEFT OUTER JOIN bookings ON trips.id = bookings.id_trip AND bookings.deleted=false 
LEFT OUTER JOIN persons ON bookings.id = persons.id_booking AND persons.deleted=false 
left join agencies ag1 on ag1.id=bookings.id_agency and ag1.deleted=false and ag1.name LIKE '%conscience%' 
left join agencies ag2 on ag2.id=trips.id_agency ag2.deleted=false 
    where 
    ag1.name LIKE '%conscience%' 
    OR ag2.name LIKE '%conscience%' 
    OR bookings.groupname LIKE '%conscience%' 
    OR persons.name LIKE '%conscience%' 
    OR fleet.name LIKE '%conscience%' 
    ORDER BY trips.timestamp 
    DESC LIMIT 0,100