使用查询别名与另一个表MySQL连接 [英] Using alias of a query to join with another table MySQL

问题描述

我有3张桌子.

support_works =包含序列号
kickscooters =序列号，kickscooter_id(作为主ID，并命名为ID)
租金=包含kickscooter_id.

support_works = contain serial_number
kickscooters = contian serial_number, kickscooter_id(as primary id, and named id)
rents = contain kickscooter_id.

我正在尝试获取满足条件的support_works的序列号，然后将其与kickscooter的序列号进行匹配.然后获取其kickscooter_id，以获取与其匹配的与kickscooter_id相匹配的所有租金.

I am trying to get serial_number of support_works that satisfy conditions then match it with kickscooter's serial_number. Then get its kickscooter_id to get all rents that match kickscooter_id retrieved from it.

当前:

select k.id
     from support_works sw
     join kickscooters k
       on k.serial_number = sw.serial_number
     where
       sw.work_type = 'deploy' and
       (sw.updated_at between '2019-11-01 02:00:00' and '2019-11-01 10:00:00') and 
       k.id in (select kcu.kickscooter_id
                from kickscooter_control_units kcu
                where kcu.particle_product_id in (9358, 9383)));

这非常适合从kickscooter表中获取kickscooter_id.但是我现在使用它作为子查询来获取所有租金表数据，其中该子查询中包含了rents.kickscooter_id:

this works perfectly on getting kickscooter_id from kickscooter table. But I am now using this as subquery to get all rents table data where rents.kickscooter_id is in this subquery:

select *
from rents r
where r.kickscooter_id
  in (select k.id
     from support_works sw
     join kickscooters k
       on k.serial_number = sw.serial_number
     where
       sw.work_type = 'deploy' and
       (sw.updated_at between '2019-11-01 02:00:00' and '2019-11-01 10:00:00') and 
       k.id in (select kcu.kickscooter_id
                from kickscooter_control_units kcu
                where kcu.particle_product_id in (9358, 9383)));

这花费了太长时间，我想使用多个联接来加快处理速度.我该怎么办?

This is taking too long and I want to use multiple joins to make things faster. How can I go about it?

我一直在使用CTE，但是我已经读到它在创建/删除临时表时会占用内存，因此尝试避免使用它.

I have been using CTE however I've read that it takes up memory while creating/deleting temporary table therefore tried to avoid it.

推荐答案

您可以使用exists关键字(而不是IN)在subquery上加入kickscooter_control_units.

You can join kickscooter_control_units on your subquery the use exists keyword rather than IN.

select *
from rents r
where 
  exists 
  (select 1
     from support_works sw
     join kickscooters k on k.serial_number = sw.serial_number
     join kickscooter_control_units kcu on  kcu.kickscooter_id =  k.id and kcu.particle_product_id in (9358, 9383)   
     where
       sw.work_type = 'deploy' and
       (sw.updated_at between '2019-11-01 02:00:00' and '2019-11-01 10:00:00'))  

似乎根据您的情况过滤了ID. exists仅在您要检查某些subquery是否包含值时适用.

Seems based on your scenario you are filtering the ID. exists only applicable if you want to check if certain subquery contains values.

 select *
    from rents r
    where 
      r.kickscooter_id in 
      (select k.id
         from support_works sw
         join kickscooters k on k.serial_number = sw.serial_number
         join kickscooter_control_units kcu on  kcu.kickscooter_id =  k.id and kcu.particle_product_id in (9358, 9383)   
         where
           sw.work_type = 'deploy' and
           (sw.updated_at between '2019-11-01 02:00:00' and '2019-11-01 10:00:00'))  

这篇关于使用查询别名与另一个表MySQL连接的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！