表结构

CREATE TABLE Movie              
(  title CHAR(20) NOT NULL,     --电影名称year INT NOT NULL,            --拍摄年份length INT ,                  --长度inColor BIT DEFAULT 1,        --是否彩色studioName CHAR(20),          --所属电影公司producerCertID CHAR(10),      --制片人PRIMARY KEY (title,year), 
);CREATE TABLE StarsIn                      
(  movieTitle CHAR(20),                   --电影名称movieYear INT ,                         --拍摄年份starName CHAR(20),                      --演员姓名PRIMARY KEY(movieTitle,movieYear,starName),FOREIGN KEY(movieTitle, movieYear) REFERENCES Movie(title,year) 
);

表样例

Movie表：

title	year	length	inColor	studioName	producerCertID
M1	2018	100	1	st1	0001
M2	2018	100	1	st1	0002
M3	2019	100	1	st2	0003
M4	2017	100	1	st2	0004
M5	2014	100	1	st2	0004
M6	2015	100	1	st2	0004
M7	2018	95	1	st2	0003

StarsIn表：

movieTitle	movieYear	starName
M1	2018	S1
M2	2018	S1
M3	2019	S2
M4	2017	S3
M3	2019	S3
M3	2019	S4
M7	2018	S2

输出样例：

starName
S1

SELECT distinct starName   #distinct:确保数据大量时输出不同的结果
FROM StarsIn
WHERE movieYear=2018 AND movieTitle IN (SELECT title FROM MovieWHERE studioName='st1' and year=2018); 

第二个条件里的year限制也很重要，本人认为是由于Movie表里是title和year两个属性联合做主码，而StarsIn表里参照的外码是Movie里的主码因此 限制条件要特别声明年份