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superkey candidate key primary key
superkey candidate key primary key ¬†using -'sql,oracle,primary-key,relational,candidate'
can any kind soul clarify my doubts with a sample example below for the superkey, candidate key and primary key.
I know there are alot of posts and websites out there explaining what's the differences between them. But it looks like all are generic definition.
Below shows my following example:
Student (StudentNumber, FamilyName, Degree, Major, Grade, PhoneNumber)
So from the above example, I can know StudentNumber confirm is a primary key.
But as for superkey, i'm abit confused of which are the combination of attributes. Which are the attributes that could be grouped into the superkey?
As for candidate key, i'm confused by the definition given as any candidate key can be qualify as a primary key.
Is it meaning that attributes such as phonenumber is a candidate key and can be a primary key? (Assuming that a phonenumber only belongs to one student) ¬†
Thanks for any clarification!
Sep 9, 2015
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