How can I do the composite key in the database?

Question

I want to creat table that include just two culmon and both are foreign key.. which that two will be primary key.. how can I do that in mysql?

Answer 1

Just set both of them as primary key. It automatically become a composite key. So if you have folkowing values
column1 | column2
1 | 6
1 | 3
There will be no error

Answer 2

Thank u a lot

Answer 3

So if I use this query

ALTER TABLE Orders
ADD FOREIGN KEY (PersonID) REFERENCES Persons(PersonID);

For both column it will be correct yes?

Answer 4

👩🏻__🇴🇲 You have to set the ON UPDATE constraint to CASCADE

ALTER TABLE Orders
ADD FOREIGN KEY (PersonID) REFERENCES Persons(PersonID)
ON UPDATE CASCADE