组合主键作为外键删除一组删除所有

composite primary key as foreign key deleting one set delets all

我有两个 table,其中一个有复合主键,另一个有外键。它们都设置为级联删除。问题是,当我删除时,假设从主 table 中删除了一个复合键集 "name: John date: 02.02.2018",所有 John 行都从 table 中删除了外键,但是可以有一个集合 "name: John date: 04.04.2018" 以及日期为 02.02.2018 的所有行也被删除我怎样才能删除只有外键集匹配的行?

更新:

CREATE TABLE messages (
    session_date date NOT NULL,
    chat int(11) NOT NULL,
    message longtext NOT NULL,
    date time NOT NULL,
    receiver int(11) NOT NULL,
    PRIMARY KEY (date,receiver),
    KEY FK_messages_sessions (session_date,chat),
    KEY FK_messages_sessions_2 (chat,session_date),
    CONSTRAINT FK_messages_sessions 
        FOREIGN KEY (session_date) 
        REFERENCES sessions (session_date) 
        ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT FK_messages_sessions_2 
       FOREIGN KEY (chat) 
       REFERENCES sessions (chat) 
       ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1

您定义了两个外键而不是复合外键。

尝试:

CREATE TABLE `messages` (
  `session_date` date NOT NULL,
  `chat` int(11) NOT NULL,
  `message` longtext NOT NULL,
  `date` time NOT NULL,
  `receiver` int(11) NOT NULL,
  PRIMARY KEY (`date`,`receiver`),
  KEY `FK_messages_sessions` (`session_date`,`chat`),
  CONSTRAINT `FK_messages_sessions` 
      FOREIGN KEY (`session_date`, `chat`) 
      REFERENCES `sessions` (`session_date`, `chat`) 
      ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1

(session_date,chat) 也可以是 (chat,session_date),具体取决于引用的 table.

中定义的主键中这些列的顺序