SQL 根据2列查询重复行

Question

我有 3 tables movie、rating 和 reviewer

movie 有 4 列 movieID、title、year、director

rating 有 4 列 reviewerID、movieID、stars、ratingDate

reviewer 有 2 列 reviewerID、name

如何查询 reviewer 谁对同一部电影评分超过 1 次，并在第二次评论时给予更高评分。

这是我尝试查询在 2 列中查找具有重复值的行（这意味着该电影已被 1 位评论者不止一次评分），然后我需要以某种方式查询 reviewer 谁给了更高的评价stars 第二次审核。

SELECT reviewer.name, movie.title, rating.stars, rating.ratingDate
FROM rating
INNER JOIN reviewer ON reviewer.rID = rating.rID
INNER JOIN movie ON movie.mID = rating.mID
WHERE rating.rID IN (SELECT rating.rID FROM rating GROUP BY rating.rID, rating.mID HAVING COUNT(*) > 1)
ORDER BY reviewer.name, rating.ratingDate;

movie table

movieID	Title	Year	Director
101	Gone with the Wind	1939	Victor Fleming
102	Star Wars	1977	George Lucas
103	The Sound of Music	1965	Robert Wise
104	E.T.	1982	Steven Spielberg
105	Titanic	1997	James Cameron
106	Snow White	1937	null
107	Avatar	2009	James Cameron
108	Raiders of the Lost Ark	1981	Steven Spielberg

rating table

reviewerID	movie ID	Stars	ratingDate
201	101	2	2011-01-22
201	101	4	2011-01-27
202	106	4	null
203	103	2	2011-01-20
203	108	4	2011-01-12
203	108	2	2011-01-30
204	101	3	2011-01-09
205	103	3	2011-01-27
205	104	2	2011-01-22
205	108	4	null
206	107	3	2011-01-15
206	106	5	2011-01-19
207	107	5	2011-01-20
208	104	3	2011-01-02

reviewer table

reviewerID	Name
201	Sarah Martinez
202	Daniel Lewis
203	Brittany Harris
204	Mike Anderson
205	Chris Jackson
206	Elizabeth Thomas
207	James Cameron
208	Ashley White

预期结果

Reviewer	Title
Sarah Martinez	Gone with the Wind

编辑：我正在使用 MySQL 版本 8.0.29

Answer 1

我们不需要将 where in 与 rating 和 join 与 rating

一起使用

您可以尝试使用 lead window 函数来获取下一个开始，每个 reviewerID 和 movieID 表示重复评级 (order by ratingDate)

然后与你的逻辑进行比较，找到一个新的开始大于旧的开始。

SELECT DISTINCT r.Name,m.Title
FROM (
  SELECT reviewerID, 
         movieID,
         Stars,
         LEAD(Stars) OVER(PARTITION BY reviewerID, movieID ORDER BY ratingDate) n_start
  FROM rating 
) t1
INNER JOIN movie m ON t1.movieID = m.movieID
INNER JOIN reviewer r ON r.reviewerID = t1.reviewerID
WHERE Stars < t1.n_start

此样本数据sqlfiddle由@ErgestBasha提供

Answer 2

使用：

select re.Name,mo.Title
FROM (
      select reviewerID,movieID,ratingDate,Stars
      from rating r 
      where exists (select 1 
              from rating r1 
              where r1.reviewerID=r.reviewerID 
              and r.movieID=r1.movieID 
              and r.ratingDate>r1.ratingDate
              and r.Stars>r1.Stars
       )) as t1
inner join movie mo on t1.movieID=mo.movieID
inner join reviewer re on t1.reviewerID=re.reviewerID

https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=0c5d850ee3393b054d9af4c4ac241d96

关键部分是EXISTS语句

where exists (select 1 
              from rating r1 
              where r1.reviewerID=r.reviewerID 
              and r.movieID=r1.movieID 
              and r.ratingDate>r1.ratingDate
              and r.Stars>r1.Stars

这将 return 只有同一用户拥有不止一部电影的结果，根据 ratingDate

评分星星比之前的大

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