Question

I am doing some SQL exercise and having this problem, this query below gives me a ‘half correct’ result because I only want the row(s) with the most title to be displayed, this query is displaying all records. Can someone help? Thanks.

Question:

Which were the busiest years for ‘John Travolta’. Show the number of movies he made for each year.

Tables:

• movie (id, title, yr, score, votes, director)
• actor (id, name)
• casting (movieid, actorid, ord)

Query:

select yr, max(title)
from 
(
select yr, count(title) title from movie
join casting
on (movie.id=casting.movieid)
join actor
on (casting.actorid=actor.id)
where actor.name="John Travolta"
group by yr Asc
) a

Answer 1

The question asks

Which were the busiest years?

… plural. So, what were his top 5 years?

select top 5
 m.yr
,count(*)
from actor as a
    join casting as c
        join movie as m
        on m.movieid = c.movieid
    on c.actorid = a.actorid
where a.name = 'John Travolta'
group by
 m.yr
order by
 count(*) desc

However, the second part of the question specifies that you should

Show the number of movies he made for each year.

So far our query doesn’t account for years in which John made no movies… so, this might be where your half correct comes into play. That said, you may want to create a table variable filled with year values from 1954 through the current year… and left join off of that.

declare @year table
(
    [yr] int
)
declare @currentYear int = datepart(year,getdate())
while @currentYear >= 1954 begin -- Travolta was born in 1954!

    insert @year values (@currentYear)
    set @currentYear -= 1

end

select
 y.yr
,count(m.movieid)
from @year y
    left join movies as m
        join casting as c
            join actor as a
            on a.actorid = c.actorid
            and a.name = 'John Travolta'
        on c.movieid = m.movieid
    on m.yr = y.yr
group by
 y.yr
order by
,count(m.movieid) desc

[Edit: based on comments] And a final query to return all years whose count matches the highest of any year.

;with TravoltaMovies as
(
    select
     m.yr
    ,count(*) as [Count]
    from actor as a
        join casting as c
            join movie as m
            on m.movieid = c.movieid
        on c.actorid = a.actorid
    where a.name = 'John Travolta'
    group by m.yr
)
select
*
from TravoltaMovies as tm
where tm.[Count] = (select max([Count]) from TravoltaMovies)