MySQL-来自一个表的许多外键

Question

im making database for game... the problem is I don't know much about databases. Here are my tables i have problem with:

CREATE TABLE items(
name VARCHAR(30) PRIMARY KEY,
type VARCHAR(20) NOT NULL,
atk INT,
def INT,
arm INT,
price_buy SMALLINT UNSIGNED,
price_sell SMALLINT UNSIGNED);

CREATE TABLE equipment (
id_eq INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
head_s VARCHAR(30),
body_s VARCHAR(30),
right_s VARCHAR(30),
left_s VARCHAR(30),
feet_s VARCHAR(30),
slot1 VARCHAR(30),
slot2 VARCHAR(30),
slot3 VARCHAR(30),
slot4 VARCHAR(30),
slot5 VARCHAR(30),
slot6 VARCHAR(30),
slot7 VARCHAR(30),
slot8 VARCHAR(30),
slot9 VARCHAR(30),
slot10 VARCHAR(30).
FOREIGN KEY (head_s) REFERENCES items(name),
FOREIGN KEY (body_s) REFERENCES items(name),
FOREIGN KEY (right_s) REFERENCES items(name),
FOREIGN KEY (left_s) REFERENCES items(name),
FOREIGN KEY (feet_s) REFERENCES items(name),
FOREIGN KEY (slot1) REFERENCES items(name),
FOREIGN KEY (slot2) REFERENCES items(name),
FOREIGN KEY (slot3) REFERENCES items(name),
FOREIGN KEY (slot4) REFERENCES items(name),
FOREIGN KEY (slot5) REFERENCES items(name),
FOREIGN KEY (slot6) REFERENCES items(name),
FOREIGN KEY (slot7) REFERENCES items(name),
FOREIGN KEY (slot8) REFERENCES items(name),
FOREIGN KEY (slot9) REFERENCES items(name),
FOREIGN KEY (slot10) REFERENCES items(name));

I have doubts about this solution, could anyone tell me is this the right way?

Answer 1

In general, this is not the right way, unless you have exactly 7 slots that are labelled 1 though 7 and you are putting items into some or all of them.

The more typical way is a junction table:

create table EquipmentItems (
    EquipmentItemId int primary key auto_increment,
    EquipmentId int,
    ItemId int,
    constraint fk_equipmentitems_equipment foreign key (EquipementId) references Equipement(id_eq),
    constraint fk_equipmentitems_item foreign key (ItemId) references items(ItemId)
);

If you look at this carefully, you'll note that I added a synthetic key to Items . This is a good idea for foreign key references, because integers are generally more compact than strings.