自学SQL网之学习笔记（题目+答案）

最近在重新学习数据库SQL，这里分享一下在使用《自学SQL网》上自学期间所涉及的练习题。

重要的事情要说三遍！仅供参考！仅供参考！仅供参考！！！

当然也悄悄种草一下这个网站练练手还是蛮不错的~

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SQL Lesson 1: SELECT 查询 101

1. 找到所有电影的名称title
   SELECT title FROM movies;
2. 找到所有电影的导演
   SELECT director FROM movies;
3. 找到所有电影的名称和导演
   SELECT title,director FROM movies;
4. 找到所有电影的名称和上映年份
   SELECT title,year FROM movies;
5. 找到所有电影的所有信息
   SELECT * FROM movies;
6. 找到所有电影的名称,Id和播放时长
   SELECT title,id,length_minutes FROM movies;
7. 请列出所有电影的ID,名称和出版国(即美国)
   SELECT id,title,"美国" as Country  FROM movies;

 

SQL Lesson 2: 条件查询 (constraints) (Pt. 1)

1. 找到id为6的电影
   SELECT * FROM movies where id = 6;
2. 找到在2000-2010年间year上映的电影
   SELECT * FROM movies where year between 2000 and 2010;
3. 找到不是在2000-2010年间year上映的电影
   SELECT * FROM movies where year not between 2000 and 2010;
4. 找到头5部电影
   SELECT * FROM movies limit 5;
5. 找到2010（含）年之后的电影里片长小于两个小时的片子
   SELECT * FROM movies where year >=2010 and length_minutes < 120;
6. 找到99年和09年的电影,只要列出年份和片长看下
   SELECT year,length_minutes FROM movies where year =1999 or year =2009;

 

SQL Lesson 3: 条件查询(constraints) (Pt. 2)

1. 找到所有Toy Story系列电影
   SELECT * FROM movies where title like "%Toy Story%";
2. 找到所有John Lasseter导演的电影
   SELECT * FROM movies where director like "John Lasseter%";
3. 找到所有不是John Lasseter导演的电影
   SELECT * FROM movies where director not like "John Lasseter%";
4. 找到所有电影名为 "WALL-" 开头的电影
   SELECT * FROM movies where title like "%Wall%";
5. 有一部98年电影中文名《虫虫危机》请给我找出来
   SELECT * FROM movies where year =1998;
6. 找出所有Pete导演的电影,只要列出电影名,导演名和年份就可以
   SELECT title,director,year FROM movies where director like "%Pete%"
7. John Lasseter导演了两个系列，一个Car系列一个Toy Story系列,请帮我列出这John Lasseter导演两个系列千禧年之后(含千禧年)的电影
   SELECT * FROM movies where director="John Lasseter"and year>= 2000
    

SQL Lesson 4: 查询结果Filtering过滤 和 sorting排序

1. 按导演名排重列出所有电影(只显示导演)，并按导演名正序排列
   SELECT distinct director FROM movies order by director;
2. 列出按上映年份最新上线的4部电影
   SELECT * FROM movies order by year desc limit 4;
3. 按电影名字母序升序排列，列出前5部电影
   SELECT * FROM movies order by title asc limit 5;
4. 按电影名字母序升序排列，列出上一题之后的5部电影
   SELECT * FROM movies order by title asc limit 5 offset 5;
5. 如果按片长排列，John Lasseter导演导过片长第3长的电影是哪部，列出名字即可
   SELECT title FROM movies where director="John Lasseter" order by length_minutes desc limit 1 offset 2
6. 按导演名字母升序,如果导演名相同按年份降序,取前10部电影给我
   SELECT * FROM movies order by director asc,year desc limit 10;

 

SQL Review: 复习 SELECT 查询

1. 列出所有加拿大人的Canadian信息(包括所有字段)
   SELECT * FROM north_american_cities where country="Canada";
2. 列出所有美国United States的城市按纬度从北到南排序(包括所有字段)

SELECT * FROM north_american_cities WHERE Longitude < '-87.629798' ORDER BY Longitude ASC;

1. 列出所有在Chicago西部的城市，从西到东排序(包括所有字段)
   SELECT * FROM north_american_cities where longitude<-87.629798 order by longitude asc;
2. 用人口数population排序,列出墨西哥Mexico最大的2个城市(包括所有字段)

SELECT * FROM North_american_cities where Country = 'Mexico' order by population desc limit 2;

1. 列出美国United States人口3-4位的两个城市和他们的人口(包括所有字段)
   SELECT * FROM north_american_cities where country='United States' order by population desc limit 2 offset 2;
2. 北美所有城市,请按国家名字母序从A-Z再按人口从多到少排列看下前10位的城市(包括所有字段)
   SELECT * FROM north_american_cities order by country asc,population desc limit 10;

 

SQL Lesson 6: 用JOINs进行多表联合查询

1. 找到所有电影的国内Domestic_sales和国际销售额
   SELECT * FROM Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id;
2. 找到所有国际销售额比国内销售大的电影
   SELECT * FROM Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id where demostic_sales < international_sales;
3. 找出所有电影按市场占有率rating倒序排列
   SELECT * FROM Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id where demostic_sales < international_sales order by rating asc;
4. John Lasseter导演的每部电影每分钟值多少钱,告诉我最高的3个电影名和价值就可以
   SELECT director,international_sales FROM Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id order by international_sales limit 1;

 

SQL Lesson 7: 外连接（OUTER JOINs）

1. 找到所有有雇员的办公室(buildings)名字
   SELECT distinct building FROM employees where building is not null;
2. 找到所有办公室和他们的最大容量
   SELECT * FROM buildings;
3. 找到所有办公室里的所有角色（包含没有雇员的）,并做唯一输出(DISTINCT)
   SELECT distinct buildings.building_name,employees.role FROM buildings left join employees on employees.building=buildings.building_name;
4. 找到所有有雇员的办公室(buildings)和对应的容量
   SELECT distinct building,capacity FROM employees left join buildings on employees.building=buildings.building_name where employees.building is not null;

 

SQL Lesson 8: 关于特殊关键字 NULLs

1. 找到雇员里还没有分配办公室的(列出名字和角色就可以)
   SELECT name,role FROM employees where Building is null;
2. 找到还没有雇员的办公室
   SELECT Building_name FROM Buildings left join Employees on Buildings.Building_name = Employees.Building where name is null;

 

SQL Lesson 9: 在查询中使用表达式

1. 列出所有的电影ID,名字和销售总额(以百万美元为单位计算)
   SELECT id,title,(domestic_sales+international_sales)/1000000 as "销售总额" FROM Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id;
2. 列出所有的电影ID,名字和市场指数(Rating的10倍为市场指数)
   SELECT id,title,rating*100 as "市场指数" FROM Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id;
3. 列出所有偶数年份的电影，需要电影ID,名字和年份
   SELECT id,title,year from Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id where year%2=0;
4. John Lasseter导演的每部电影每分钟值多少钱,告诉我最高的3个电影名和价值就可以
   SELECT title,(domestic_sales+international_sales)/length_minutes as “价值” from Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id where director = “Jhon Lasseter” order by “价值” limit 3;
5. 电影名最长的3部电影和他们的总销量是多少
   SELECT，length(title) as title_len,title,(domestic_sales + international_sales) as “总销量” from Movies left join Boxoffice on Movies.Id = Boxoffice.Movie_id order by title_len desc limit 3;

 

SQL Lesson 10: 在查询中进行统计I (Pt. 1)

1. 找出就职年份最高的雇员(列出雇员名字+年份）
   SELECT name,max(years_employed) from employees;
2. 按角色(Role)统计一下每个角色的平均就职年份
   SELECT role,avg(years_employed) from employees group by role;
3. 按办公室名字总计一下就职年份总和
   SELECT building,sum(years_employed) from employees group by building
4. 每栋办公室按人数排名,不要统计无办公室的雇员
   SELECT building,count(*) as count from employees where building is not null group by building
5. 就职1,3,5,7年的人分别占总人数的百分比率是多少(给出年份和比率"50%" 记为 50)
   SELECT years_employed,count(*)*100/(select count(*) from employees) as rating from employees where years_employed in (1,3,5,7) group by years_employed

 

SQL Lesson 11: 在查询中进行统计I (Pt. 2)

1. 统计一下Artist角色的雇员数量
   SELECT count(*) from employees where role = “Artist”;
2. 按角色统计一下每个角色的雇员数量
   SELECT role,count(*) from employees where group by role;
3. 算出Engineer角色的就职年份总计
   SELECT sum(Years_employed) FROM employees where role = "Engineer";
4. 每栋办公室按人数排名,不要统计无办公室的雇员
   SELECT count(*) as count,Role,building is not null as bn FROM employees group by Role,bn
5. 就职1,3,5,7年的人分别占总人数的百分比率是多少(给出年份和比率"50%" 记为 50)
   SELECT Role,Years_employed/3 as year_3,count(*) as count FROM employees group by Role,year_3 order by count desc

 

SQL Lesson 12: 在查询中进行统计I (Pt. 2)

1. 统计出每一个导演的电影数量（列出导演名字和数量）
   SELECT director,count(*) FROM movies group by director
2. 统计一下每个导演的销售总额(列出导演名字和销售总额)
   SELECT director,sum(domestic_sales+international_sales) as "总销售额" FROM movies left join boxoffice on movies.id=boxoffice.movie_id group by director
3. 按导演分组计算销售总额,求出平均销售额冠军（统计结果过滤掉只有单部电影的导演，列出导演名，总销量，电影数量，平均销量)
   SELECT director,sum(Domestic_sales + International_sales) AS sum_sales,count(director),sum(Domestic_sales + International_sales)/count(director) AS avg_sales FROM movies LEFT JOIN boxoffice ON movies.id = boxoffice.movie_id group by director having count(director) > 1 ORDER BY avg_sales DESC LIMIT 1
4. 找出每部电影和单部电影销售冠军之间的销售差，列出电影名，销售额差额
   select title ,(select max(international_sales+domestic_sales) from boxoffice)-(international_sales+domestic_sales) AS Margin from movies left join boxoffice on movies.id=boxoffice.movie_id