只能有一个外键引用主键吗？

Question

When creating a table and a database in do the foreign keys need to be unique?

For example

Table: Manifest

Manifest_Barcode - PK
Vehicle_reg - FK
weight
description

Table: Vehicle

vechicle_reg - PK
employee_ID - FK
make
model

Table: Drivers

employee_ID - PK
vechicle_reg - FK
name
adress
phone_Number
year

Or, can I use the same foreign key in 2 different tables? Like the above?

Answer 1

It is completely appropriate and quite normal to have multiple FOREIGN KEYs that refer to the same PRIMARY KEY. They are not the same FOREIGN KEY (they will each build a separate index to use in enforcing the key), they are different FOREIGN KEYs with similar definitions.

Note that you will have to create the table vehicle1 before declaring either of the FOREIGN KEYs.