sql-聚合最大功能和分组依据

Question

select city, title, releasedate
from movies join shownat on shownat.movietitle = movies.title join theatres on theatres.theatrename = shownat.theatrename
group by city, title, releasedate
order by city, max(releasedate) desc;

Above is my query, and this problem to solve.

Find the titles of the newest movies shown in each city. Display the city name and the newest movie title ordered by city name and movie title.

The normalized data has 3 tables called theatres, shownat and movies. Yes, I realize the release date could be more efficient on the shownat table, and to me it makes more sense because not always are videos always released in same areas or cities at the same date. However it is my last homework problem that I am stuck on. What is needed is that the city should only have 1 listing. I thought that the group by city would take care of this. For each city I need the title of the movie that has the newest release date in each of the particular cities(4) in the data set. I am unsure as to why I am getting duplicates here when I have the group by feature for this and its use to handle the aggregate max function. The max function should just give me the newest release yes?

"CITY"          "TITLE"        "RELEASEDATE"
"Cincinnati"    "Interstellar"  07-NOV-14
"Cincinnati"    "Big Hero 6"    07-NOV-14
"Cincinnati"    "Nightcrawler"  31-OCT-14
"Cincinnati"    "Gone Girl"     03-OCT-14
"Cincinnati"    "The Pianist"   03-JAN-03
"Cincinnati"    "Fargo" 05-APR-96
"Cincinnati"    "Schindler's List"  04-FEB-94
"Florence"      "Big Hero 6"    07-NOV-14
"Florence"      "Interstellar"  07-NOV-14
"Florence"      "Nightcrawler"  31-OCT-14
"Florence"  "Gone Girl" 03-OCT-14
"Florence"  "District 9"    14-AUG-09
"Florence"  "A Perfect Getaway" 07-AUG-09
"Florence"  "Aliens in the Attic"   31-JUL-09
"Florence"  "Away We Go"    26-JUN-09
"Florence"  "Up"    29-MAY-09
"Florence"  "Star Trek" 08-MAY-09
"Florence"  "The Hurt Locker"   10-OCT-08
"Florence"  "The Dark Knight"   18-JUL-08
"Florence"  "The Departed"  06-OCT-06
"Florence"  "The Green Mile"    10-DEC-99
"Newport"   "Interstellar"  07-NOV-14
"Newport"   "Big Hero 6"    07-NOV-14
"Newport"   "Gone Girl" 03-OCT-14
"Newport"   "District 9"    14-AUG-09
"Newport"   "A Perfect Getaway" 07-AUG-09
"Newport"   "Away We Go"    26-JUN-09
"Newport"   "Up"    29-MAY-09
"Newport"   "The Departed"  06-OCT-06
"Wilder"    "Big Hero 6"    07-NOV-14
"Wilder"    "Interstellar"  07-NOV-14
"Wilder"    "Gone Girl" 03-OCT-14
"Wilder"    "Public Enemies"    01-JUL-09
"Wilder"    "The Departed"  06-OCT-06

Answer 1

This would be the query but I'm not quite sure if max function would works with a date variable:

SELECT city, title, max (releasedate) as max_dateRelease
FROM movies inner join shownat on shownat.movietitle = movies.title join theatres 
on theatres.theatrename = shownat.theatrename
GROUP BY city, title, releasedate
ORDER BY city, max_dateRelease desc

Answer 2

select T1.city,T2.movietitle,T1.releasedate
from
(select city,max(releasedate) as maxreleasedate
from movies join shownat on shownat.movietitle = movies.title join theatres on theatres.theatrename = shownat.theatrename
group by city) as T1
inner join
(select shownat.movietitle,shownat.city,shownat.releasedate)
from shownat) as T2
 on T1.city=T2.city and T1.maxreleasedate=T2.releasedate

This is one way and isn't best way.