SQL查詢花費的時間太長（LEFT OUTER JOIN）

Question

我一直在測試用於查詢提議的SQL查詢，以便從“車隊”，“行程”，“預訂”，“代理商”和“人員”列中獲取數據。

問題是此查詢花費的時間太長（2分鍾）才能完成。 我嘗試使用“ WHERE”和/或“ INNER JOIN”，但查詢時間減少到了幾毫秒，但是並不能滿足我想要的所有結果。 例如，“行程”中有一些條目沒有與“預訂”相關聯，或者有些“預訂”條目中沒有與“人員”相關聯。 這就是為什么我需要使用LEFT OUTER JOIN的原因，但這使查詢非常緩慢。

我相信這種語法存在效率問題，但我不知道這是什么。

我希望結果是這樣的：

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

查詢已更新：

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

您可以與agencies一起加入表格，而不是使用多個子查詢，這應該會給您相同的結果，請嘗試對您有所幫助：

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