Describe the main characteristics of the Relational Data Model, including the properties of relations and the rules for relational integrity.
What will be an ideal response?
Relational
– set of tables (as perceived by users)
– rows/columns
– variety of possible storage structures
– no repeating groups
– no links/pointers
– use of join columns.
– no duplicate tuples
– tuples are unordered
– attributes are unordered
– all attribute values are atomic.
Entity Integrity: No attribute participating in the PK of a base relation is allowed to accept null
values.
Referential Integrity: If a base relation R2 includes a FK targeting the PK of R1, then every
value of FK must either be:
– equal to the value of PK in some tuple of R1 or
– wholly null.
You might also like to view...
The customer role and the supplier role involve the same assumptions and operate similarly.
Answer the following statement true (T) or false (F)
Each member of the Keys enumeration is a(n) ________ representing a keyboard key.
a) string b) double c) Key d) int e) object
In a Word document, the default margins are _____.
A. 1.5" B. 1" C. 0.75" D. 0.5"
Windows allows users to interact with the operating system using tabs instead of menus
Indicate whether the statement is true or false