mysql - 关于sql语句中的with从句和group by分组

Question

初涉SQL，对于其中with和group by从句搭配sum，max方法的使用逻辑有一些疑问 例如，数据库中有以下几个table {代码...} 要output出 carbrand。这个carbrand是最多distinct customer使用过的，即求每一种carbrand...

伊谢尔伦 · Answer

The question is to choose "passengers' favorite car model". The following Postgresql code is not tested:

select carbrand, count(*) as customers
from (
  select distinct carbrand, cusid
  from Trips inner join Car using (carid)) as brand_cusid
group by carbrand
order by customers desc
limit 10

brand_cusid is the model-passenger relationship table, which has been distinct processed. brand_cusid是车型-乘客的关系表，已做distinct处理。
然后按carbrand分组并按行数从大到小排序，并显示前10个车型。
注意这些车型有可能是并列第一的。这时可增加limit

Then group by carbrand and sort by row number from large to small, and display the top 10 models. 🎜🎜 🎜🎜Note that these models may be tied for first place. At this time, the limit quantity can be increased. 🎜🎜 🎜