Week_5 Flashcards
1
Q
Name 4 Relational Keys.
A
- Superkey
- Candidate key
- Primary key
- Foreign key
2
Q
What is a Superkey?
A
An attribute or set of attributes that uniquely identifies a tuple within a relation.
3
Q
What is meant by Null?
A
Null represents the “value” for an attribute that is currently unknown or not applicable for the tuple. (Represents the absence of a value and is not the same as zero or spaces which are values)
