Explain the Database Designing Steps (Or) What are the main steps of Database Designing?
https://www.computersprofessor.com/2016/06/explain-database-designing-steps-or.html
The database design is considered to be the
most important task while following database approach for a reality. Therefore,
Database design is the Process of constructing a stable DB structures from the
User requirement Analysis.
The database design
structures the grouping of Fields/Attributes into different files and
establishes meaningful associations between different Files in an Optimal
manner, which helps to minimize the response time while accessing and
manipulating Databse during its use.
Thus, one must be analyze
the user requirements, identify the basic needs and find the correct means of
logical representation to accomplish the Conceptual Datamodel.
STEPS OF DATABASE DESIGN:
The database designing
steps can be categorized into
1.
Requirement Analysis
2.
Design of Conceptual Data Model
3.
Design of Internal Data Model or Implementation Design and
4.
Design of Physical Data Model.
Requirement Analysis:
The first step of the DB design is
to perform requirement Analysis. The requirements of the users of the proposed
system are to be identified either through interviews with the members
concerned or through reports that are presently used by the users. Thus, the format of each and every report is
to be collected along with related processing requirements such as Periodicity
and nature of each report etc.
From each report, you can
obtain
· Name of the report
·
List of Data items from the report to be stored in the
Database and
·
Each Data element in each of the report
·
Associations between different data items
·
Name of Data Item, its Data Type (Char, Numeric, Date,
Logical etc), its width
·
Update authority
·
Allowable range (if data item is Numeric) and
·
Source of Data item etc.
Design of Conceptual Data
Model:
It is a Logical Data model. It
is the process of designing a DBMS independent Data Model, which gives a stable
comprehensive View of the entire Database. The basic input for this step is,
the set of relations of different reports from the user views.
The Conceptual Data Model
is, thus, an independent of a specific model of the 3 types of Data models,
such as, Hierarchical Data Model,
Network Data Model and Relational Data Model. It gives a Conceptual
foundation of the organization of different files and related associations
between them. Finally, the conceptual Data model is mapped into any ONE of the
3 above data models in reality, then the mapped Data Model becomes DBMS Dependent.
The steps of designing a
Conceptual DM can be summarized as,
§ Input the requirement
specifications in the form of relations
§ Apply Normalization on
each and every relation up to a specified level of Normalized Form
§ Perform View Integration
§ Construct a Stable
Conceptual Data Model
§ Design LAM (Logical Access
Map) for each user view.
NORMALIZATION is the
process of Functional dependency analysis which helps to split the relations of
each user view into stable sub groups of Data items. Each sub groups of fields
is called a File.
VIEW INTEGRATION is the
process of merging the sub groups of data items of different user views, which
are having the same key field(s).
CONSTRUCTION OF A
CONCEPTUAL DM, means, organizing the
final set of files obtained through the view integration into a meaningful
schema with relevant associations between different files in it.
LOGICAL ACCESS MAP
(LAM) is a kind of flow chart defined
over the Conceptual DM to access and manipulate it to print a report/ user
view.
Therefore, before mapping
the Conceptual DM into any DBMS dependent DM , One has to do a careful analysis
by taking the following factors into consideration.
1.
The best of the 3 DM’s
should be able to completely define the realistic problem on hand.
2.
Due to financial constraints, if it is not possible to
procure the related S/w tool to access the best fitting DM or, if there is no
expert available with in the company or, there is difficulty in recruiting
persons with the required skills/ expertise, then one can choose the best
fitting Data Model.
Design of Internal Data
Model: After designing the Conceptual
DM, (which is independent to the Database environment), it should be implemented/ Mapped into any one
of the following Data Models.
I.
Hierarchical Data Model
II.
Network Data Model and
III.
Relational Data Model
Selecting the right type
of DM, to suit the reality is an important task, since it will improve the
efficiency of operations of the system. The implementation design is an
important step of the database design , which decides the selection of the best
fitting DM and maps the conceptual DM into the selected DM.
Steps of Implementation Design:
1.
Input the following
a) DBMS
Independent Schema/ Conceptual DM
b)
Data Volume and Usage Details
c) Characteristics
of the selected DBMS Datamodel
2. Map the
Conceptual DM into the desired Logical DM
3. Design
sub-schemas of different users of the system
4. Prepare Program
design guidelines for each sub schema
5. Perform review
design and carry out corrections, if any
Design of Physical Data
Model: After designing the Internal Data
Model, the next step is to design a Physical Data Model. It is concerned with deciding the following
factors.
a) Stored record format
b) Selecting Accessing
methods
c) Database Security
d) Integrity
e) Back up procedures
f) Recovery Methods etc.
Thus the design of physical data model decides the data storage, its location and accessing methods with required security measures.
