Question

列出所有在1950年代和1980年代拍摄电影的演员。

当我专门尝试时：

SELECT a.name
FROM movies AS m
JOIN castings AS c
JOIN actors AS a
ON m.id = c.movieid
AND c.actorid = a.id
WHERE (m.yr BETWEEN 1950 AND 1959)

或：

SELECT a.name
FROM movies AS m
JOIN castings AS c
JOIN actors AS a
ON m.id = c.movieid
AND c.actorid = a.id
WHERE (m.yr BETWEEN 1980 AND 1989)

我得到两个单独查询的结果。但是，当我合并这些行时，没有任何行。

SELECT a.name
FROM movies AS m1
JOIN movies AS m2
JOIN castings AS c
JOIN actors AS a
ON m1.id = c.movieid
AND m2.id = c.movieid
AND c.actorid = a.id
AND m1.id < m2.id
WHERE (m1.yr BETWEEN 1950 AND 1959) AND (m2.yr BETWEEN 1980 AND 1989);

如何找到要查找的名称？

Answer 1

从现有查询开始，一种简单的方法是使用聚合，并使用HAVING子句进行过滤：

SELECT a.name
FROM movies AS m
JOIN castings AS c ON m.id = c.movieid
JOIN actors AS a ON c.actorid = a.id
GROUP BY a.id, a.name
HAVING 
    MAX(m.yr BETWEEN 1950 AND 1959) = 1 
    AND MAX(m.yr BETWEEN 1980 AND 1989) = 1

Answer 2

您可以在where子句中使用子查询。

SELECT 
    a.name 
FROM
    actors AS a 
WHERE EXISTS 
    (SELECT 
        1 
    FROM
        movies m,
        castings c 
    WHERE c.actorid = a.id 
        AND m.id = c.movieid 
        AND (m.yr BETWEEN 1950 
            AND 1959) 
    LIMIT 1) 
    OR EXISTS
    (SELECT 
        1 
    FROM
        movies m,
        castings c 
    WHERE c.actorid = a.id 
        AND m.id = c.movieid 
        AND (m.yr BETWEEN 1980 
            AND 1989) 
    LIMIT 1)

或者您可以在获取电影数量的同时使用以下分组方式：

SELECT 
    a.name,
    SUM(IF(m.yr BETWEEN 1950 AND 1959, 1, 0)) AS e1950,     -- Number of Movies in 1950s
    SUM(IF(m.yr BETWEEN 1980 AND 1989, 1, 0)) AS e1980      -- Number of Movies in 1980s
FROM movies AS m
JOIN castings AS c
JOIN actors AS a
ON m.id = c.movieid
AND c.actorid = a.id
GROUP BY a.name HAVING e1950 > 0 AND e1980 > 0;

MySQL-连接和之间

2 个答案: