CIS4365: Database Applications
Fall, 2017

How are Relational DBMS classified?

There are four types of classification for Relational DBMS:

Classification Characters
Fully Relational.

  1. Supports all eight relational algebra functions.

  2. Enforces both entity and referential integrity rules.

Relational Complete.

  1. Supports all relational algebra functions

  2. Does not support integrity rule.

Minimally Relational.

          Supports only on SELECT, PROJECT and JOIN functions.
Tabular.
  1. Supports only SELECT, PROJECT and JOIN functions.
  2. It requires that all access paths be defined by the user.

The Standard to define these classifications base on eight relational algebra functions:

  1. Select function
  2. Join function
  3. Projection function
  4. Difference function
  5. Cartesian Product function
  6. Union function
  7. Intersection function
  8. Divide function

Multiple choices:

1. What type of relational algebra functions will be accepted by minimally rational?

A. Intersection function, Join function and Divide function

B. Select function, Project function and Join function

C. Union function, Select function and Divide function

D. None of above.

Answer: B

Short questions:

1. How does Join function work?

Answer:

It combines recordsets based on the comparison of one or more common fields.

2. What's the requirement for entity integrity rule?

Answer:

Null value is not allowed in this primary key field