是否可以在一个表中引用一个主键作为跨越两个以上表的外键约束？

Question

I am currently making a database back end system on an airport, using sql through the phpmyadmin server. The criteria is not meant to be perfect but one of the ideas behind the queries is to imagine that either a customer or flight dispatch officer might be looking at the tables. I was wondering if it was possible to reference a primary key as a foreign key across 2 or more tables. In the example below, I want to reference the model number as a foreign key in the bottom 2 tables. I have ensured that the type and character count are the same.

    CREATE TABLE Aircraft_Model
    (Model_Number varchar (12) NOT NULL,
    seat_capacity int (3),
    CONSTRAINT pk7 primary key (Model_Number));

    CREATE TABLE Licence_type
    (Rank varchar (25) NOT NULL,
    Model_Number varchar (12),
    CONSTRAINT pk9 primary key (Rank));

    CREATE TABLE Aircraft
    (Aircraft_ID varchar (4) NOT NULL, 
    Model_Number varchar(12),
    airport_base text(13),
    CONSTRAINT pk1 PRIMARY KEY (Aircraft_ID));

Is this possible? I only want the database to be able to perform about 12-15 simple queries.

Would the syntax of adding a foreign key be something like this?

ALTER TABLE Aircraft
ADD CONSTRAINT fk1 FOREIGN KEY(Model_Number)
REFERENCES Aircraft_Model

Does the same foreign key being referenced from a separate table such as Licence_type need a separate constraint to be added or can it be added from the same one with the same fk1 number?

Answer 1

I was wondering if it was possible to reference a primary key as a foreign key across 2 or more tables.

If you mean, "Can two or more tables have foreign keys that reference the same column?", then, yes, you can do that. This seems to be what you mean, but it's not what most people mean when they talk about "a foreign key across 2 or more tables".

Declare two different, separate constraints.

ALTER TABLE Aircraft
ADD CONSTRAINT fk1 FOREIGN KEY(Model_Number)
REFERENCES Aircraft_Model (Model_Number);

ALTER TABLE License_Type
ADD CONSTRAINT fk2 FOREIGN KEY(Model_Number)
REFERENCES Aircraft_Model (Model_Number);