SQL Server：多个事务

Question

select 
    STUDIO.NAME, MOVIE.TITLE, MOVIE.YEAR
from 
    STUDIO 
join 
    MOVIE on STUDIO.NAME = MOVIE.STUDIONAME
where 
    MOVIE.YEAR >= ALL (select MOVIE.YEAR from MOVIE)

I have this code which give me as a result the year of the last film, it's title and the name of the studio, which make the movie.

How can I rewrite this code, so I can get the last produced movie by each studio, not only by one?

Answer 1

Try:

SELECT a.NAME,
       a.TITLE,
       a.YEAR
FROM (select s.NAME, 
       m.TITLE, 
       m.YEAR,
       ROW_NUMBER()OVER(PARTITION BY s.NAME ORDER BY m.YEAR DESC ) as rnk
from STUDIO s
join MOVIE m on s.NAME = m.STUDIONAME) a
WHERE a.rnk = 1

Answer 2

SELECT *
FROM (
SELECT STUDIO.NAME, MOVIE.TITLE, MOVIE.YEAR
from 
    STUDIO 
join 
    MOVIE on STUDIO.NAME = MOVIE.STUDIONAME
ORDER BY MOVIE.YEAR DESC
) AS newTable
GROUP BY newTable.NAME

Answer 3

The answer above is fine for finding the most recent year a studio published a movie, however if you need the title too, using that method you'll need to use some form of subselect to get the largest year (and so the most recent) by studio name, and then bring in the title based on this.

The below does both in a fairly succinct fashion using a CROSS APPLY:

SELECT 
S.NAME,
MM.TITLE
MM.YEAR
FROM STUDIO S
CROSS APPLY 
    (SELECT TOP 1 TITLE, YEAR FROM MOVIE M
     WHERE M.STUDIONAME = S.STUDIO
     ORDER BY M.YEAR DESC) MM

1st Edit: Added context 2nd Edit: Added edit notes.

Answer 4

You might try something like

select 
    studio.name, 
    movie.title, 
    movie.year
from 
    studio 

    inner join movie on 
      studio.name = movie.studioname

    inner join 
    (
        select
          movie.studioname
          max(movie.year) year
        from
          movie
    ) t1 on
      t1.studioname = studio.studioname and
      t1.year = movie.year

Note that there are limitations to the way you have written your query:

• There could be multiple movies in the same year - which one is the latest? You would need a date column for that or something that that affect
• Also you are using varchar/chars to join on which is really bad practice since you have to do a string comparison on each match. It would be better to use id - integers - which give better performance

Answer 5

What do you mean "not only by one"?

Normally you do such queries using aggregate functions:

select STUDIO.NAME, MOVIE.TITLE, MAX( MOVIE.YEAR )
from STUDIO 
join MOVIE on STUDIO.NAME = MOVIE.STUDIONAME
Group by STUDIO.NAME, MOVIE.TITLE

Is this what you need?