Mysql

mishu2024年9月26日小于 1 分钟

去重

delete from Person where id not in (
	select id from (
		select min(id) as id from Person group by email
	) T
)

delete p1 from Person  p1, Person  p2
where p1.Email = p2.Email  and  p1.id > p2.id

row_number, rank(), dense_rank()的区别及具体用法示例 - 知乎 (zhihu.com)
dense_rank() 1 1 2 3 4 5
rank() 1 1 3 4 5 6
row_number() 1 2 3 4 5 6

SELECT
  score,
  DENSE_RANK() over (
    order by
      score desc
  ) as 'rank'
FROM
  Scores;