unit 4.3 Flashcards
1
Q
A
2
Q
Constraint types
A
Domain,key,Referential Integrity
3
Q
Domain constraints
A
Domain expansion, tested easily by the system
4
Q
If a field has no value, NULL should be used instead of an empty string or a zero value.
A
Ouais
5
Q
Key constraints(uniqueness constraints
A
Key constraints make sure that each row in a table is unique (no two rows can be the same).
surrogate,identity,sequence
6
Q
Referential Integrity Constraints :
A
Foreign keys, data consistency
7
Q
Data accessing
A
Sequential- till the end
Direct-
Index Sequential Method- hybrid
8
Q
A
8
Q
Types of File Organization
A
Sequential- pile,sorted
Heap- file is added one after the other
Hash- takes an attribute (such as a key) and maps it to a specific location in the file
