Question

1. These three terms all refer to the same part of a database: True or False

• Instance
• Row
• Field

  2. When compared to File Processing systems, select each of the following that are advantages of a database system. Note: there may be more than one right answer.

  Group of answer choices;

  A. Shorter development times.

  B. If the data structure changes, a program may not need to be changed.

  C. The data does not need to be duplicated.

  D. There is very little if any program-data dependence

• 3. Describe the difference between a logical data model and a physical data model.

Answer 1

Question#1

Correct Answer:-

False

Explanation:-

Instance, Row and field do not refer to same part of the database. A row is a tuple which is an entry into some table of the database, whereas a field is a column or attribute of the database. And finally, an instance refers to some sort of storage structure of the database.

Question#2

Correct Answer:-

B & C

(If the data structure changes, a program may not need to be changed)

(The data does not need to be duplicated)

Explanation:-

B - In Database systems, program and data are independent unlike file processing systems. Means changing or modifying either of them won't have any effect on the other one.

C - As there is a lot of redundancy (duplication) in file processing systems but Database systems provide reduced redundancy. We have to normalize the whole database to remove duplications from it.

Other option are wrong as A (A database system is time consuming & it is costly) and D (A DB system is completely program-data independent so there is no point of talking about a chance).

Question#3

Answer:-

Both data models describe requirements for a single project or an application.

Logical Data Model:-

A logical model represents a data model independent of database. It determines visual/business representation of data model and relationships between data elements.
This model is created by expert business analysts and developed independently from database.
Its main purpose is to give basis for creating a physical data model.
In logical data model, we also normalize database to 3rd Normal Form.
It is platform, hardware and software independent.

Physical Data Model:-

It helps determining different views which describe how to implement a specific database.
It's main purpose is the implementation of the data-model related to that particular database.
It is created by database developer (Database Administrators).
It is designed for a specific platform, hardware & software and specific version of DBMS, storage and technology.
Tables' fields will have exact data types and lengths.
In it, we also define primary and foreign keys.

-------------------------------------------------------------------
COMMENT DOWN FOR ANY QUERIES!!!
HIT A THUMBS UP IF YOU DO LIKE IT!!!