Relational Calculus

Question 1

Formal query language for relational model based on the branch of the mathematical logic called predicate calculus

Answer 1

Relational Calculus

Question 2

Specify what is to be retrieved rather than how to retrieve it

Answer 2

Relational Calculus

Question 2

Two variations of relational Calculus

Answer 2

tuple
domain

Question 2

Importance of Relational Calculus

Answer 2

1. Firm basis in mathematical Logic
2. SQL has its basic foundation in tuple relational calculus

Question 3

{t|COND(t)} the first t represents?

Answer 3

tuple variable representing the requested attributes

Question 4

{t|COND(t)} the COND(t) represents?

Answer 4

conditional expression involving t that evaluates to TRUE or FALSE

Question 4

formula is made up of predicate calculus atoms which can be

Answer 4

An atom of the form:
R(ti)
ti. A op tj. B
ti. A op c or c op tj.B

Question 5

COND is called _________ or ________

Answer 5

condition or formula or well informed formula

Question 6

A formula is made up of one or more atoms connected via ___________

Answer 6

Logical operators ie. and or and not

Question 6

Two special symbols called _______ can appear in formulas

Answer 6

quantifiers
Existential quantifier ∃
- A formula ∃t (F) is TRUE if there exists some tuple t that makes F TRUE.
Universal quantifier ∀
- A formula ∀t (F) is TRUE if for all possible tuple t, F is TRUE.

Question 7

Query Graph

Answer 7

Graphical representation of a relational calculus query