国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Table des matières
Preface
Presentation
Question Details
Answer
Initialization:
Insert Values
Solution 8
Reference
Maison base de données tutoriel mysql 數(shù)據(jù)庫題目整理及詳解英文版(五)

數(shù)據(jù)庫題目整理及詳解英文版(五)

Jun 07, 2016 pm 02:50 PM
base de données rangé Version anglaise Explication détaillée

Preface when there is rain neither sun nor moon, the people actually do not think so. Perhaps there are seasonal climate not to be cold rain, let the sun or the cool side. Has the rain the night is otherwise a moonlit night no flavor. Some


Preface

when there is rain neither sun nor moon, the people actually do not think so.

Perhaps there are seasonal climate not to be cold rain, let the sun or the cool side.

Has the rain the night is otherwise a moonlit night no flavor.

Sometimes not reminiscent of Li Shangyin “when he cut a total of west window candle, but then when the famous hope of reunion among friends”

In the rain, fom the sky come the silk notes; here, quiet and comfortable.

in rain


Presentation

In this page, we will show the homework of the course of the Databases Technology in CMU. All of the questions we tested in the postgresql.

This section mainly is to practice the query operation of the SQL, include SQL view, index, etc. We also sure that all the sqls will pass in the mysql, sqlite… , this article also will provide the Chinese version in detail.

中文版


Question Details

In this homework you will have to write SQL queries to answer questions on a movie dataset, about movies and actors. The database contains two tables:

? movies(mid, title, year, num ratings, rating) , Primary key: mid
? play in(mid, name, cast position), Primary key: mid, name

The tables contain the obvious information: which actor played in what movie, at what position; for each movie, we have the title (eg., ’Gone with the wind’), year of production, count of rating reviews it received, and the average score of those ratings (a float in the range 0 to 10, with ’10’ meaning ’excellent’).


We will use Postgres, which is installed in the your own machines.

Question 1: Warm-up queries … … … … … … … … . [5 points]
(a) [2 points] Print all actors in the movie Quantum of Solace, sorted by cast position. Print only their names.
(b) [3 points] Print all movie titles that were released in 2002, with rating larger than 8 and with more than one rating (num ratings > 1).


Question 2: Find the star’s movies … … … … … … . . [5 points]
(a) [5 points] Print movie titles where Sean Connery was the star (i.e. he had position 1 in the cast). Sort the movie titles alphabetically.


Question 3: Popular actors … … … … … … … … . . [15 points]
(a) [8 points] We want to find the actors of the highest quality. We define their quality as the weighted average of the ratings of the movies they have played in (regardless of cast position), using the number of ratings for each movie as the
weight. In other words, we define the quality for a particular actor as

計算公式

Print the names of the top 5 actors, according to the above metric. Break ties alphabetically.

(b) [7 points] Now we want to find the 5 most popular actors, in terms of number of ratings (regardless of positive or negative popularity). I.e, if actor ‘Smith’ played in 2 movies, with num ratings 10 and 15, then Smith’s popularity is 25 (=10+15). Print the top 5 actor names according to popularity. Again, break ties alphabetically.


Question 4: Most controversial actor … … … … … . [10 points]
(a) [10 points] We want to find the most controversial actor. As a measure of controversy, we define the maximum difference between the ratings of two movies that an actor has played in (regardless of cast position). That is, if actor ‘Smith’ played in a movie that got rating=1.2, and another that got rating=9.5, and all the other movies he played in, obtained scores within that range, then Smith’s contoversy score is 9.5-1.2= 8.3. Print the name of the top-most controversial actor - again, if there is a tie in first place, break it alphabetically.


Question 5: The minions … … … … … … … … … . [20 points]
(a) [20 points] Find the “minions” of Annette Nicole: Print the names of actors who only played in movies with her and never without her. The answer should not contain the name of Annette Nicole. Order the names alphabetically.


Question 6: High productivity … … … … … … … … [5 points]
(a) [5 points] Find the top 2 most productive years (by number of movies produced). Solve ties by preferring chronologically older years, and print only the years.


Question 7: Movies with similar cast … … … … … . [15 points]
(a) [8 points] Print the count of distinct pairs of movies that have at least one actor in common (ignoring cast position). Exclude self-pairs, and mirror-pairs.
(b) [7 points] Print the count of distinct pairs of moves that have at least two actors in common (again, ignoring cast position). Again, exclude self-pairs, and mirror pairs.


Question 8: Skyline query … … … … … … … … … [25 points]
(a) [25 points] We want to find a set of movies that have both high popularity (ie, high num ratings) as well as high quality (rating). No single movie may achieve both - in which case, we want the so-called Skyline query 2 . More specifically, we want all movies that are not “dominated” by any other movie:

Definition of domination : Movie “A” dominates movie “B” if movie “A” wins over movie “B”, on both criteria, or wins on one, and ties on the rest.

Figure 1 gives a pictorial example: the solid dots (’A’, ’D’, ’F’) are not dominated by any other dot, and thus form the skyline. All other dots are dominated by at least one other dot: e.g., dot ’B’ is dominated by dot ’A’, being inside the shaded rectangle that has ’A’ as the upper-right corner.

figure 1

Figure 1: Illustration of Skyline and domination : ’A’ dominates all points in the shaded rectangle; ’A’, ’D’ and ’F’ form the skyline of this cloud of points.

Given the above description, print the title of all the movies on the skyline, along with the rating and the number of ratings.


Answer

we give the Postgres version in detail, we will see you can tranfer it easily in mysql or sqlite.

Initialization:

<code class=" hljs sql">## <span class="hljs-operator"><span class="hljs-keyword">drop</span> the <span class="hljs-keyword">table</span> <span class="hljs-keyword">if</span> <span class="hljs-keyword">exists</span>
<span class="hljs-keyword">drop</span> <span class="hljs-keyword">table</span> <span class="hljs-keyword">if</span> <span class="hljs-keyword">exists</span> movies <span class="hljs-keyword">cascade</span>;</span>   
<span class="hljs-operator"><span class="hljs-keyword">drop</span> <span class="hljs-keyword">table</span> <span class="hljs-keyword">if</span> <span class="hljs-keyword">exists</span> play_in <span class="hljs-keyword">cascade</span>;</span>

## <span class="hljs-operator"><span class="hljs-keyword">create</span> tables movies <span class="hljs-keyword">and</span> play_in
<span class="hljs-keyword">create</span> <span class="hljs-keyword">table</span> movies (
mid <span class="hljs-keyword">integer</span> <span class="hljs-keyword">PRIMARY</span> <span class="hljs-keyword">KEY</span>, 
title <span class="hljs-keyword">varchar</span>(<span class="hljs-number">200</span>),
<span class="hljs-keyword">year</span> <span class="hljs-keyword">integer</span>,
num_ratings <span class="hljs-keyword">integer</span>, 
rating <span class="hljs-keyword">real</span>);</span>

<span class="hljs-operator"><span class="hljs-keyword">create</span> <span class="hljs-keyword">table</span> play_in (
mid <span class="hljs-keyword">integer</span> <span class="hljs-keyword">references</span> movies, 
name <span class="hljs-keyword">varchar</span>(<span class="hljs-number">100</span>), 
cast_position <span class="hljs-keyword">integer</span>, 
<span class="hljs-keyword">PRIMARY</span> <span class="hljs-keyword">KEY</span>(mid, name));</span>

<span class="hljs-operator"><span class="hljs-keyword">create</span> index mid <span class="hljs-keyword">on</span> movies(mid);</span></code>

Insert Values

Insert into some values into the table movies and play_in,
you will find the datas just in the follow links in my 360 yunFiles:

https://yunpan.cn/cSfLzxQApRXSi password: f3ab

<code class=" hljs rust">## <span class="hljs-keyword">use</span> <span class="hljs-string">"copy"</span> in Postgres
\<span class="hljs-keyword">copy</span> movies from <span class="hljs-string">'~/data/movie_processed.dat'</span>;
\<span class="hljs-keyword">copy</span> play_in from <span class="hljs-string">'~/data/movie_actor_processed.dat'</span>;

## <span class="hljs-keyword">if</span> you <span class="hljs-keyword">use</span> other databases(mysql, sqlite), you can <span class="hljs-keyword">use</span>   the sql statement: <span class="hljs-string">"insert into ... valuse()"</span>
</code>

The flowing image show the test infos in my ubuntu os:

ctreate and copy datas1

ctreate and copy datas2


Solution 1

<code class=" hljs asciidoc">(a) SELECT name FROM play<span class="hljs-emphasis">_in p, movies m
WHERE p.mid = m.mid and m.title=’Quantum of Solace’
ORDER BY p.cast_</span>position;

## (a) Result just like this:

<span class="hljs-header">name
------------------------------</span>
Daniel Craig
Olga Kurylenko
Mathieu Amalric
Judi Dench
Giancarlo Giannini
Gemma Arterton
Jeffrey Wright
David Harbour
Jesper Christensen
Anatole Taubman
Rory Kinnear
Tim Pigott-Smith
Fernando Guillen-Cuervo
Jesus Ochoa
Glenn Foster
Paul Ritter
Simon Kassianides
Stana Katic
Lucrezia Lante della Rove...
Neil Jackson
Oona Chaplin
(21 rows)

(b) SELECT title FROM movies
WHERE year = 2002 and rating>8 and num<span class="hljs-emphasis">_ratings>1;

</span>## (b) Result just like this:
<span class="hljs-header">title
---------------------------------------</span>
The Lord of the Rings: The Two Towers
Cidade de Deus
Mou gaan dou
(3 rows)
</code>

The flowing image show the test solution 1 infos in my ubuntu os:

3

3.1

4


Solution 2

<code class=" hljs vbnet"><span class="hljs-keyword">SELECT</span> title <span class="hljs-keyword">from</span> movies m, play_in p
<span class="hljs-keyword">WHERE</span> m.<span class="hljs-keyword">mid</span> = p.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span> 
name = ’Sean Connery’ <span class="hljs-keyword">and</span> 
cast_position = <span class="hljs-number">1</span>
<span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span> title;

<span class="hljs-preprocessor">## Result just like this:</span>
title
---------------------------------------
Der Name der Rose
Diamonds Are Forever
Dr. No
Entrapment
Finding Forrester
First Knight
<span class="hljs-keyword">From</span> Russia <span class="hljs-keyword">with</span> Love
Goldfinger
Never Say Never Again
The Hunt <span class="hljs-keyword">for</span> Red October
The League <span class="hljs-keyword">of</span> Extraordinary Gentlemen
Thunderball
You Only Live Twice
(<span class="hljs-number">13</span> rows)</code>

The flowing image show the test solution 2 infos in my ubuntu os:

5


Solution 3

<code class=" hljs sql">(a) <span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> WeigthedRatings;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> WeightedRatings <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> name, <span class="hljs-aggregate">SUM</span>(rating*num_ratings)/<span class="hljs-aggregate">SUM</span>(num_ratings) <span class="hljs-keyword">AS</span> WeightedRating
<span class="hljs-keyword">FROM</span> movies m, play_in p <span class="hljs-keyword">WHERE</span> m.mid = p.mid <span class="hljs-keyword">GROUP</span> <span class="hljs-keyword">BY</span>(name);</span>

<span class="hljs-operator"><span class="hljs-keyword">SELECT</span> name <span class="hljs-keyword">FROM</span> WeightedRatings
<span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span>
WeightedRating <span class="hljs-keyword">DESC</span>, name <span class="hljs-keyword">ASC</span> LIMIT <span class="hljs-number">5</span>;</span>

## (a) Result just like this:
name
<span class="hljs-comment">-----------------------</span>
Adam Kalesperis
Aidan Feore
Aleksandr Kajdanovsky
Alexander Kaidanovsky
Alisa Frejndlikh
(5 rows)

(b) <span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> ActorSumRatings;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> ActorSumRatings <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> name, <span class="hljs-aggregate">SUM</span>(num_ratings) <span class="hljs-keyword">as</span> popularity
<span class="hljs-keyword">FROM</span> play_in p, movies m
<span class="hljs-keyword">WHERE</span> p.mid = m.mid
<span class="hljs-keyword">GROUP</span> <span class="hljs-keyword">BY</span> name;</span>

<span class="hljs-operator"><span class="hljs-keyword">SELECT</span> name <span class="hljs-keyword">from</span> ActorSumRatings
<span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span> popularity <span class="hljs-keyword">DESC</span>, name <span class="hljs-keyword">ASC</span> LIMIT <span class="hljs-number">5</span>;</span>

## (b) Result just like this:
name
<span class="hljs-comment">----------------------</span>
Johnny Depp
Alan Rickman
Orlando Bloom
Helena Bonham Carter
Matt Damon
(5 rows)</code>

The flowing images show the test solution 3 infos in my ubuntu os:

6

7


Solution 4

<code class=" hljs sql"><span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> RatingGap;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> RatingGap <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> p1.name, <span class="hljs-aggregate">MAX</span>(ABS(m1.rating-m2.rating)) <span class="hljs-keyword">as</span> Gap
<span class="hljs-keyword">FROM</span> play_in p1, play_in p2, movies m1, movies m2
<span class="hljs-keyword">WHERE</span> p1.mid = m1.mid <span class="hljs-keyword">and</span> 
p2.mid = m2.mid <span class="hljs-keyword">and</span> 
p1.name = p2.name
<span class="hljs-keyword">GROUP</span> <span class="hljs-keyword">BY</span>(p1.name);</span>

<span class="hljs-operator"><span class="hljs-keyword">SELECT</span> name 
<span class="hljs-keyword">FROM</span> RatingGap 
<span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span>(Gap) <span class="hljs-keyword">DESC</span> LIMIT <span class="hljs-number">1</span>;</span>

## Result just like this:
name
<span class="hljs-comment">---------------</span>
John Travolta
(1 row)</code>

The flowing image show the test solution 4 infos in my ubuntu os:

8.1

8.3


Solution 5

<code class=" hljs sql"><span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> MastersMovies <span class="hljs-keyword">CASCADE</span>;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> MastersMovies <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> m.mid,m.title <span class="hljs-keyword">FROM</span> movies m, play_in p
<span class="hljs-keyword">WHERE</span> m.mid = p.mid <span class="hljs-keyword">and</span> p.name = ’Annette Nicole’;</span>

<span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> CoActors;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> CoActors <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> <span class="hljs-keyword">DISTINCT</span> name <span class="hljs-keyword">FROM</span> MastersMovies m , play_in p
<span class="hljs-keyword">WHERE</span> p.mid = m.mid;</span>

<span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> Combinations;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> Combinations <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> name,mid <span class="hljs-keyword">FROM</span> MastersMovies , CoActors;</span>

<span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> NonExistent;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> NonExistent <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> * <span class="hljs-keyword">FROM</span> Combinations
<span class="hljs-keyword">EXCEPT</span> (<span class="hljs-keyword">SELECT</span> name, mid <span class="hljs-keyword">FROM</span> play_in);</span>

<span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> PotentialResults;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> PotentialResults <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> * <span class="hljs-keyword">from</span> CoActors
<span class="hljs-keyword">EXCEPT</span> (<span class="hljs-keyword">SELECT</span> <span class="hljs-keyword">distinct</span>(name) <span class="hljs-keyword">FROM</span> NonExistent);</span>

<span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> NotMastersMovies;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> NotMastersMovies <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> m.mid <span class="hljs-keyword">FROM</span> movies m
<span class="hljs-keyword">EXCEPT</span> (<span class="hljs-keyword">SELECT</span> mid <span class="hljs-keyword">FROM</span> MastersMovies);</span>

<span class="hljs-operator"><span class="hljs-keyword">SELECT</span> * <span class="hljs-keyword">from</span> PotentialResults
<span class="hljs-keyword">WHERE</span> name <span class="hljs-keyword">not</span> <span class="hljs-keyword">in</span> 
(<span class="hljs-keyword">SELECT</span> name
<span class="hljs-keyword">FROM</span> play_in p, NotMastersMovies m
<span class="hljs-keyword">WHERE</span> m.mid = p.mid
<span class="hljs-keyword">UNION</span> <span class="hljs-keyword">SELECT</span> ’Annette Nicole’
) <span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span> name;</span>

## Result just like this:
name
<span class="hljs-comment">-----------------</span>
Christian Perry
(1 row)
</code>

The flowing image show the test solution 5 infos in my ubuntu os:

8.2


Solution 6

<code class=" hljs sql"><span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> MoviesPerYear;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> MoviesPerYear <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> <span class="hljs-keyword">year</span>, <span class="hljs-aggregate">COUNT</span>(title) num_movies
<span class="hljs-keyword">FROM</span> MOVIES <span class="hljs-keyword">GROUP</span> <span class="hljs-keyword">BY</span>(<span class="hljs-keyword">year</span>);</span>

<span class="hljs-operator"><span class="hljs-keyword">SELECT</span> <span class="hljs-keyword">year</span> <span class="hljs-keyword">from</span> MoviesPerYear 
<span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span> num_movies <span class="hljs-keyword">DESC</span> LIMIT <span class="hljs-number">2</span>;</span>

## Result just like this:
year
<span class="hljs-comment">------</span>
2006
2007
(2 rows)</code>

The flowing image show the test solution 6 infos in my ubuntu os:

9


Solution 7

<code class=" hljs vbnet">(a) <span class="hljs-keyword">SELECT</span> COUNT(*) <span class="hljs-keyword">FROM</span> 
(<span class="hljs-keyword">SELECT</span> <span class="hljs-keyword">DISTINCT</span> m1.<span class="hljs-keyword">mid</span>, m2.<span class="hljs-keyword">mid</span>
 <span class="hljs-keyword">FROM</span> movies m1, movies m2, play_in p1, play_in p2
 <span class="hljs-keyword">WHERE</span> m1.<span class="hljs-keyword">mid</span> > m2.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span>
 m1.<span class="hljs-keyword">mid</span> = p1.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span>
 m2.<span class="hljs-keyword">mid</span> = p2.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span> 
 p1.name = p2.name) 
<span class="hljs-keyword">AS</span> count;

<span class="hljs-preprocessor">## (a) Result just like this:</span>
count
--------
<span class="hljs-number">104846</span>
(<span class="hljs-number">1</span> row)

(b) <span class="hljs-keyword">SELECT</span> COUNT(*) <span class="hljs-keyword">FROM</span> 
(<span class="hljs-keyword">SELECT</span> <span class="hljs-keyword">DISTINCT</span> m1.<span class="hljs-keyword">mid</span>, m2.<span class="hljs-keyword">mid</span>
<span class="hljs-keyword">FROM</span> movies m1, movies m2, play_in p1,
play_in p2, play_in p3, play_in p4
<span class="hljs-keyword">WHERE</span> m1.<span class="hljs-keyword">mid</span> > m2.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span> 
m1.<span class="hljs-keyword">mid</span> = p1.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span> 
m2.<span class="hljs-keyword">mid</span> = p2.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span>
m1.<span class="hljs-keyword">mid</span> = p3.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span> 
m2.<span class="hljs-keyword">mid</span> = p4.<span class="hljs-keyword">mid</span> <span class="hljs-keyword">and</span> 
p2.name <> p4.name <span class="hljs-keyword">and</span> 
p1.name = p2.name <span class="hljs-keyword">and</span> 
p3.name = p4.name) 
<span class="hljs-keyword">AS</span> count;

<span class="hljs-preprocessor">## (b) Result just like this:</span>
count
-------
<span class="hljs-number">6845</span>
(<span class="hljs-number">1</span> row)</code>

The flowing image show the test solution 7 infos in my ubuntu os:

11


Solution 8

<code class=" hljs sql"><span class="hljs-operator"><span class="hljs-keyword">DROP</span> <span class="hljs-keyword">VIEW</span> <span class="hljs-keyword">IF</span> <span class="hljs-keyword">EXISTS</span> Dominated;</span>

<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">VIEW</span> Dominated <span class="hljs-keyword">AS</span>
<span class="hljs-keyword">SELECT</span> <span class="hljs-keyword">DISTINCT</span> m2.mid, m2.title,m2.num_ratings, m2.rating
<span class="hljs-keyword">FROM</span> movies m1, movies m2
<span class="hljs-keyword">WHERE</span> m2.rating<=m1.rating <span class="hljs-keyword">and</span> m2.num_ratings<=m1.num_ratings <span class="hljs-keyword">and</span> 
<span class="hljs-keyword">NOT</span> (m2.rating = m1.rating <span class="hljs-keyword">and</span> m2.num_ratings=m1.num_ratings);</span>

<span class="hljs-operator"><span class="hljs-keyword">SELECT</span> title,num_ratings,rating 
<span class="hljs-keyword">FROM</span> movies
<span class="hljs-keyword">EXCEPT</span> (<span class="hljs-keyword">SELECT</span> title,num_ratings,rating <span class="hljs-keyword">FROM</span> Dominated);</span>
</code>

The flowing image show the test solution 8 infos in my ubuntu os:

12


Reference

[1] http://www.ruanyifeng.com/blog/2013/12/getting_started_with_postgresql.html
[2] http://www.postgresql.org/docs/
[3] http://www.cs.cmu.edu/~epapalex/15415S14/PostgreSQLReadme.htm
[4] http://www.cs.cmu.edu/~christos/courses/

Déclaration de ce site Web
Le contenu de cet article est volontairement contribué par les internautes et les droits d'auteur appartiennent à l'auteur original. Ce site n'assume aucune responsabilité légale correspondante. Si vous trouvez un contenu suspecté de plagiat ou de contrefa?on, veuillez contacter admin@php.cn

Outils d'IA chauds

Undress AI Tool

Undress AI Tool

Images de déshabillage gratuites

Undresser.AI Undress

Undresser.AI Undress

Application basée sur l'IA pour créer des photos de nu réalistes

AI Clothes Remover

AI Clothes Remover

Outil d'IA en ligne pour supprimer les vêtements des photos.

Clothoff.io

Clothoff.io

Dissolvant de vêtements AI

Video Face Swap

Video Face Swap

échangez les visages dans n'importe quelle vidéo sans effort grace à notre outil d'échange de visage AI entièrement gratuit?!

Article chaud

Outils chauds

Bloc-notes++7.3.1

Bloc-notes++7.3.1

éditeur de code facile à utiliser et gratuit

SublimeText3 version chinoise

SublimeText3 version chinoise

Version chinoise, très simple à utiliser

Envoyer Studio 13.0.1

Envoyer Studio 13.0.1

Puissant environnement de développement intégré PHP

Dreamweaver CS6

Dreamweaver CS6

Outils de développement Web visuel

SublimeText3 version Mac

SublimeText3 version Mac

Logiciel d'édition de code au niveau de Dieu (SublimeText3)

Sujets chauds

Tutoriel PHP
1502
276
iOS 18 ajoute une nouvelle fonction d'album 'Récupéré' pour récupérer les photos perdues ou endommagées iOS 18 ajoute une nouvelle fonction d'album 'Récupéré' pour récupérer les photos perdues ou endommagées Jul 18, 2024 am 05:48 AM

Les dernières versions d'Apple des systèmes iOS18, iPadOS18 et macOS Sequoia ont ajouté une fonctionnalité importante à l'application Photos, con?ue pour aider les utilisateurs à récupérer facilement des photos et des vidéos perdues ou endommagées pour diverses raisons. La nouvelle fonctionnalité introduit un album appelé "Récupéré" dans la section Outils de l'application Photos qui appara?tra automatiquement lorsqu'un utilisateur a des photos ou des vidéos sur son appareil qui ne font pas partie de sa photothèque. L'émergence de l'album ??Récupéré?? offre une solution aux photos et vidéos perdues en raison d'une corruption de la base de données, d'une application d'appareil photo qui n'enregistre pas correctement dans la photothèque ou d'une application tierce gérant la photothèque. Les utilisateurs n'ont besoin que de quelques étapes simples

Comment enregistrer les données JSON dans la base de données dans Golang ? Comment enregistrer les données JSON dans la base de données dans Golang ? Jun 06, 2024 am 11:24 AM

Les données JSON peuvent être enregistrées dans une base de données MySQL à l'aide de la bibliothèque gjson ou de la fonction json.Unmarshal. La bibliothèque gjson fournit des méthodes pratiques pour analyser les champs JSON, et la fonction json.Unmarshal nécessite un pointeur de type cible pour désorganiser les données JSON. Les deux méthodes nécessitent la préparation d'instructions SQL et l'exécution d'opérations d'insertion pour conserver les données dans la base de données.

MySQL: Concepts simples pour l'apprentissage facile MySQL: Concepts simples pour l'apprentissage facile Apr 10, 2025 am 09:29 AM

MySQL est un système de gestion de base de données relationnel open source. 1) Créez une base de données et des tables: utilisez les commandes CreateDatabase et CreateTable. 2) Opérations de base: insérer, mettre à jour, supprimer et sélectionner. 3) Opérations avancées: jointure, sous-requête et traitement des transactions. 4) Compétences de débogage: vérifiez la syntaxe, le type de données et les autorisations. 5) Suggestions d'optimisation: utilisez des index, évitez de sélectionner * et utilisez les transactions.

Tutoriel détaillé sur l'établissement d'une connexion à une base de données à l'aide de MySQLi en PHP Tutoriel détaillé sur l'établissement d'une connexion à une base de données à l'aide de MySQLi en PHP Jun 04, 2024 pm 01:42 PM

Comment utiliser MySQLi pour établir une connexion à une base de données en PHP?: Inclure l'extension MySQLi (require_once) Créer une fonction de connexion (functionconnect_to_db) Appeler la fonction de connexion ($conn=connect_to_db()) Exécuter une requête ($result=$conn->query()) Fermer connexion ( $conn->close())

Comment gérer les erreurs de connexion à la base de données en PHP Comment gérer les erreurs de connexion à la base de données en PHP Jun 05, 2024 pm 02:16 PM

Pour gérer les erreurs de connexion à la base de données en PHP, vous pouvez utiliser les étapes suivantes : Utilisez mysqli_connect_errno() pour obtenir le code d'erreur. Utilisez mysqli_connect_error() pour obtenir le message d'erreur. En capturant et en enregistrant ces messages d'erreur, les problèmes de connexion à la base de données peuvent être facilement identifiés et résolus, garantissant ainsi le bon fonctionnement de votre application.

Le r?le d'Oracle dans le monde des affaires Le r?le d'Oracle dans le monde des affaires Apr 23, 2025 am 12:01 AM

Oracle n'est pas seulement une entreprise de base de données, mais aussi un leader des systèmes de cloud computing et ERP. 1. Oracle fournit des solutions complètes de la base de données aux services cloud et aux systèmes ERP. 2. OracleCloud défie AWS et Azure, fournissant des services IaaS, PaaS et SaaS. 3. Les systèmes ERP d'Oracle tels que E-BusinessSuite et FusionApplications aident les entreprises à optimiser les opérations.

MySQL: une introduction à la base de données la plus populaire au monde MySQL: une introduction à la base de données la plus populaire au monde Apr 12, 2025 am 12:18 AM

MySQL est un système de gestion de la base de données relationnel open source, principalement utilisé pour stocker et récupérer les données rapidement et de manière fiable. Son principe de travail comprend les demandes des clients, la résolution de requête, l'exécution des requêtes et les résultats de retour. Des exemples d'utilisation comprennent la création de tables, l'insertion et la question des données et les fonctionnalités avancées telles que les opérations de jointure. Les erreurs communes impliquent la syntaxe SQL, les types de données et les autorisations, et les suggestions d'optimisation incluent l'utilisation d'index, les requêtes optimisées et la partition de tables.

Mysql vs autres bases de données: comparaison des options Mysql vs autres bases de données: comparaison des options Apr 15, 2025 am 12:08 AM

MySQL convient aux applications Web et aux systèmes de gestion de contenu et est populaire pour son open source, ses performances élevées et sa facilité d'utilisation. 1) Par rapport à PostgreSQL, MySQL fonctionne mieux dans les requêtes simples et les opérations de lecture simultanées élevées. 2) Par rapport à Oracle, MySQL est plus populaire parmi les petites et moyennes entreprises en raison de son open source et de son faible co?t. 3) Par rapport à Microsoft SQL Server, MySQL est plus adapté aux applications multiplateformes. 4) Contrairement à MongoDB, MySQL est plus adapté aux données structurées et au traitement des transactions.

See all articles