Question

我目前正忙着做家庭作业......

我们正在使用sakila db（https://dev.mysql.com/doc/sakila/en/）

练习是找到并选择每部影片，其中不止一个演员具有相同的名字并选择这些演员

e.g。

title             vn       nn
AFRICAN EGG       MATTHEW  TAUTOU
AFRICAN EGG       MATTHEW  LEIGH 
ANALYZE HOOSIERS  TOM      MCKELLEN  
ANALYZE HOOSIERS  TOM      MIRANDA

我目前使用3个表格（表格 - ＆gt; https://dev.mysql.com/doc/sakila/en/sakila-structure-tables.html）：

FILM_ACTOR
演员
膜

我目前正在选择一部电影中的每个演员，这部电影中有超过1名具有相同名字的演员：

SELECT f.title title, a.actor_id, a.first_name vn, a.last_name nn FROM film_actor fa
LEFT JOIN actor a ON a.actor_id = fa.actor_id
LEFT JOIN film f ON f.film_id = fa.film_id
WHERE fa.film_id IN
(
    SELECT fa.film_id FROM film_actor fa
    LEFT JOIN actor a ON a.actor_id = fa.actor_id
    LEFT JOIN film f ON f.film_id = fa.film_id
    GROUP BY a.first_name, f.title HAVING count(a.first_name) > 1
)
ORDER BY title;

我得到了这个结果：

title                   actor_id vn     nn
DESPERATE TRAINSPOTTING 117      RENEE  TRACY
DESPERATE TRAINSPOTTING 137      MORGAN WILLIAMS
DESPERATE TRAINSPOTTING 187      RENEE  BALL
DESPERATE TRAINSPOTTING 77       CARY   MCCONAUGHEY

我不知道如何只获取重复演员的名字...... 有什么建议吗？

Answer 1

使用COUNT(DISTINCT firstname)：

SELECT f.title title, a.actor_id, a.first_name vn, a.last_name nn
FROM film_actor fa
LEFT JOIN actor a
    ON a.actor_id = fa.actor_id
LEFT JOIN film f
    ON f.film_id = fa.film_id
INNER JOIN
(
    SELECT a.first_name, fa.film_id
    FROM film_actor fa
    LEFT JOIN actor a
        ON a.actor_id = fa.actor_id
    WHERE fa.film_id IN
    (
        SELECT fa.film_id
        FROM film_actor fa
        LEFT JOIN actor a
            ON a.actor_id = fa.actor_id
        LEFT JOIN film f
            ON f.film_id = fa.film_id
        GROUP BY fa.film_id
        HAVING COUNT(DISTINCT a.first_name) > 1
    )
    GROUP BY a.first_name, fa.film_id
    HAVING COUNT(*) > 1
) t
    ON a.first_name = t.first_name AND
       fa.film_id   = t.film_id

在您的原始尝试中，您正在检查所有名字的数量。当然，对于任何拥有多个演员的电影来说，这都是正确的。相反，你想要检查不同演员的数量。

mysql过滤器重复其他列匹配

1 个答案: