这是我尝试运行的查询，它正在工作，但现在由于某种原因，我无法弄清楚它现在放弃了。
SELECT films.movie_title, films.rating, films.actor, reviewed.review
FROM films
INNER JOIN reviewed
ON films.movie_id=reviewed.review_id
在浏览表格时，我遇到了这个问题。认为这可能是问题所在。
ALTER TABLE `reviewed`
ADD CONSTRAINT `reviewed_ibfk_1` FOREIGN KEY (`movie_id`) REFERENCES `films` (`movie_id`),
ADD CONSTRAINT `reviewed_ibfk_2` FOREIGN KEY (`movie_id`) REFERENCES `films` (`movie_id`) ON DELETE CASCADE;
--
-- Table structure for table `films`
--
CREATE TABLE IF NOT EXISTS `films` (
`movie_id` int(4) NOT NULL AUTO_INCREMENT,
`movie_title` varchar(100) NOT NULL,
`actor` varchar(100) NOT NULL,
`rating` varchar(20) NOT NULL,
PRIMARY KEY (`movie_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=23 ;
--
-- Dumping data for table `films`
--
INSERT INTO `films` (`movie_id`, `movie_title`, `actor`, `rating`) VALUES
(22, 'Batman Begins', 'Bale', 'Good');
-- --------------------------------------------------------
--
-- Table structure for table `reviewed`
--
CREATE TABLE IF NOT EXISTS `reviewed` (
`review_id` int(4) NOT NULL AUTO_INCREMENT,
`review` mediumtext NOT NULL,
`movie_id` int(4) NOT NULL,
PRIMARY KEY (`review_id`),
KEY `movie_id` (`movie_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;
--
-- Dumping data for table `reviewed`
--
INSERT INTO `reviewed` (`review_id`, `review`, `movie_id`) VALUES
(1, 'Really good film.', 22);
--
ALTER TABLE `reviewed`
ADD CONSTRAINT `reviewed_ibfk_1` FOREIGN KEY (`movie_id`) REFERENCES `films` (`movie_id`),
ADD CONSTRAINT `reviewed_ibfk_2` FOREIGN KEY (`movie_id`) REFERENCES `films` (`movie_id`) ON DELETE CASCADE;
看起来您正在加入两个主键 （films.movie_id=reviewed.review_id），而不是一个主键和一个外部键 （films.movie_id=reviewed.movie_id）。
尝试以下操作：
SELECT films.movie_title, films.rating, films.actor, reviewed.review
FROM films
INNER JOIN reviewed
ON films.movie_id=reviewed.movie_id
正如@andrewsi所提到的，您的 ON 子句似乎不正确。您正在尝试将电影 ID 与评论的 ID 匹配，这绝不应假定为 true。当 INNER JOIN 无法从 ON 子句正确匹配时，它通常不会给出任何结果。
请尝试以下查询：
SELECT films.movie_title, films.rating, films.actor, reviewed.review
FROM films
INNER JOIN reviewed
ON films.movie_id=reviewed.movie_id