mysql> USE test;
Reading TABLE information FOR completion OF TABLE AND COLUMN names
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DATABASE changed
mysql> CREATE TABLE `item` (
    ->     `id` INT(11) UNSIGNED PRIMARY KEY AUTO_INCREMENT,
    ->     `name` VARCHAR(30) NOT NULL,
    ->     `description` MEDIUMTEXT
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `image` (
    `id` INT(11) UNSIGNED AUTO_INCREMENT,
    `file` VARCHAR(255) UNIQUE NOT NULL,
    `caption` VARCHAR(255),
    PRIMARY KEY(`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;Query OK, 0 ROWS affected (0.06 sec)

mysql>
mysql> CREATE TABLE `image` (
    ->     `id` INT(11) UNSIGNED AUTO_INCREMENT,
    ->     `file` VARCHAR(255) UNIQUE NOT NULL,
    ->     `caption` VARCHAR(255),
    ->     PRIMARY KEY(`id`)
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 ROWS affected (0.06 sec)

mysql> CREATE TABLE `item_image` (
    ->     `item` INT(11) UNSIGNED NOT NULL,#foreign KEY
    ->     `img` INT(11) UNSIGNED NOT NULL,#foreign KEY
    ->     PRIMARY KEY(`item`,`img`)
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 ROWS affected (0.05 sec)

mysql> DROP TABLE item_image;
Query OK, 0 ROWS affected (0.03 sec)

mysql> CREATE TABLE `item_image` (
    ->     `item` INT(11) UNSIGNED NOT NULL,
    ->     `img` INT(11) UNSIGNED NOT NULL,
    ->     PRIMARY KEY(`item`,`img`),
    ->     FOREIGN KEY(`item`)
    ->         REFERENCES `item` (`id`)
    ->         ON DELETE CASCADE,
    ->     FOREIGN KEY(`img`)
    ->         REFERENCES `image` (`id`)
    ->         ON DELETE CASCADE
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 ROWS affected (0.08 sec)