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How can I do the composite key in the database?
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?
4 Antworten
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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
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Thank u a lot
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So if I use this query
ALTER TABLE Orders
ADD FOREIGN KEY (PersonID) REFERENCES Persons(PersonID);
For both column it will be correct yes?
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👩🏻__🇴🇲 You have to set the ON UPDATE constraint to CASCADE
ALTER TABLE Orders
ADD FOREIGN KEY (PersonID) REFERENCES Persons(PersonID)
ON UPDATE CASCADE