4

show engine innodb status;これは、テーブルを作成しようとしたときのエラーメッセージです。

------------------------
LATEST FOREIGN KEY ERROR
------------------------
110628 16:56:07 Error in foreign key constraint of table test/menu_items:
foreign key(id_menu)
                references menus(id)
                on update cascade
                on delete cascade,
        foreign key(id_item)
                references items(id)
                on update cascade
                on delete cascade,
        primary key(id_menu, id_item)
) engine=InnoDB:
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.1/en/innodb-foreign-key-constraints.html
for correct foreign key definition.

関連するSQLステートメントは次のとおりです。

create table if not exists menus (                                                                                            
    id              mediumint unsigned not null auto_increment,
    id_restaurant   mediumint unsigned not null,
    name            varchar(50) not null,
    description     varchar(255) default null,
    foreign key(id_restaurant)
        references restaurants(id)
        on update cascade
        on delete cascade,
    primary key(id)
) engine=InnoDB;

create table if not exists items (
    id              mediumint unsigned not null auto_increment,
    id_restaurant   mediumint unsigned not null,
    name            varchar(50),
    description     text,
    type            enum('appetizer','salad','soup','entree','dessert','drink','other'),
    price           decimal(4,2),
    foreign key(id_restaurant)
        references restaurants(id)
        on update cascade
        on delete cascade,
    primary key(id)
) engine=InnoDB;

create table if not exists order_items (
    id_order        bigint unsigned not null,
    id_item         mediumint unsigned not null,
    item_name       varchar(50),
    item_description    text,
    item_price      decimal(4,2),
    notes           varchar(1024),
    quantity        smallint unsigned,
    foreign key(id_order)
        references orders(id)
        on update cascade
        on delete cascade,
    foreign key(id_item)
        references items(id)
        on update cascade
        on delete cascade,
    primary key(id_order, id_item)
) engine=InnoDB;

menu_items.id_menuおよび対応する外部キー/主キーを削除すると、SQLステートメントを適切に解析できます。

menu_itemsからmenus（id）への外部キー参照を作成できないのはなぜですか？

4

1 に答える 1

15

データ型の不一致があります：

create table order_items (
    id_order bigint unsigned not null, -- BIGINT

create table items (
    id mediumint unsigned not null auto_increment, -- MEDIUMINT

ただし、order_items.id_order参照items.idするため、同じである必要があります。

order_itemsid_orderをmediumintに変更してみてください。

order_items (
    id_order        mediumint unsigned not null,
于 2011-06-28T08:18:47.243 に答える