Explain the Database Life Cycle (DBLC)?
https://www.computersprofessor.com/2017/01/explain-database-life-cycle-dblc.html
The DBLC is one of the most
important function for the database designer, application programmer & the management consult.
The DBLC contains 6 important phases. |
|
DataBase initial study :
The current has failed to perform functions, the database designer as to
examining the present systems operations with in the company. The database
designer must determine why & how the system failed? The database
designer can be interact with the end users & the people consult with
excellent communication.
|
|
Skills along with
interpersonal skills in the organization.
|
|
The overall purpose of the data
base initial study is:
|
|
¨
Analyze company situation
|
|
¨
Define the problem & constrains
|
|
¨
Define objects of the organization
|
|
¨
Define the scope & boundaries
|
|
The database initial study is an
integrative& interactive process required in the first phase of the DBLC.
If leads to the development of database. System objectives. It analyzes the
company’s situation such as how the company operates, organization structure
& its mission.
|
|
The key questions in this stage
are:
|
|
¨ What
is organization structure .
|
|
¨
The organization operating environment & its mission.
|
|
¨
How the system function.
|
|
¨
How they interact.
|
|
The database designer as to gather
both formal & informal sources of information. He has to decide.
|
|
¨ How
does the existing system function?
|
|
¨
What input does it require?
|
|
¨
What documents/reports that the system generate?
|
|
¨ By
whom & how the system output is used?
|
|
Therefore a careful analysis must
be taken by the database designer to learn & distinguish between what is
perfect & what is possible by recognizing the existence of its scope
& boundaries.
|
|
The systems scope defines the
extent of the design according to the operational requirements such as
defining the required data structures, data types & the no.of entities,
physical size of the database and so on.
|
|
The proposed system is subject to
the limits, i.e., boundaries which are external to the system the boundaries
specified the man power, companies budgets, existing hardware & software
etc.
|
|
Data base design:
|
|
The DB design phase focuses on the
design of DB model supporting companies operations & its objectives. This
is a critical & important DBLC step. Since it should mean final product to meet both user & system requirements. One has to concentrate on
data characteristics required to built in datamodel. Thus designing data is
an integral part of the DBLC’s second phase.
|
|
This phase is divided into 4 stages:
|
|
1. Conceptual
design – Data base analysis & its requirements [determine end user views,
connection processing requirements and
required output].
|
|
2. Entity
relationship modeling & normalization [define entities, attributes,
drawing ER diagrams, relationships & normalizing the tables].
|
|
3. Data model
verification [identify main processes & data anomalies].
|
|
4. Distributed
database design [Define the location tables access requirements,
fragmentation strategies].
|
|
In conceptual design stage, the
database designer analyze the company situation define the actual problems,
according to the objectives of the organization company scope &
boundaries of the system.
|
|
The data modeling is used to
detect the problem regiment, data abstraction, data types & real word
objectives. The process of defining the business rules & developing the
conceptual data model by using ER diagram to make a stable data model. The
purpose of ER diagrams is :
|
|
(a) Identify the
main entities
|
|
(b) Indentify,
analyze and pre-define the problems
|
|
(c) Define the
relationship among the entities
|
|
(d) Define the
attributes & set primary key, foreign key, constrains for each of the
entities
|
|
(e) Apply
normalization process for the entities & finally complete the initial ER
diagrams
|
|
Data model
verification:
|
|
The verification requires the data
model with a series of tasks again:
|
|
¨
Each end user data use & transfer
|
|
¨
Access part to define the data, store data & reach data for manipulation
|
|
¨
Checking constraints for validation of data and security of data
|
|
When the data in the database is
distributed across the system, the database designer must plane & develop
it as a distributed and hence provide allocation of peripheral resources
& strategies. The verification process is selecting the central entity.
The central entity defined in terms of its participation in most of the data
models relationship & the system operations with in the central entity
frame work, you must
|
|
®
Ensure the modules, cohesively
|
|
®
Cohesively describes the strength of the relationship of the relationship
among the module entities.
|
|
®
Analyse each module relationship with other modules to address module
coupling
|
|
®
Module coupling describe the extent to which modules are independent of one
another
|
|
®
Processes – must be according to their
frequency – daily, weekly, monthly, yearly, operational type – insert,
update, delete, quarries & reports
|
|
DBMS software
selection:
|
|
The selection of DBMS software is
an important & critical step to the systems smooth operation. The
database designer must describe.
|
|
¨Cost
–includes purchase price along with maintenance, operational, license,
installation, training & conversion cost
|
|
¨DBMS
features & its tools – The DBMS software includes a verify of tools that
facilitates application development task such as QBE, screen designing data
dictionary, report generators, application generators etc.
|
|
The database administrator
facilitates performance security, concurrency controls, transaction
procession.
|
|
¨
Portability – DBMS can be portable across various platforms system &
languages
|
|
¨
DBMS hardware requirements – it includes RAM, processes, disk space etc.
|
|
Local design:
|
|
It translates the conceptual
design in to the internal data model for selector DBMS such as DBI, SQL
server, My SQL, Oracle & MS-office. The logical design is software
dependent. The logical design for RDBMS includes specification of tables,
index, views, transaction, access authority etc.
|
|
Physical design:
it is the process of selecting data storage
and data characteristics of the data base. The storage characteristics are a
function of the types of devices, hardware data access methods supported by a
system. Therefore, it is a technical jobs & effects not only location of
data in the storage devices but also the performances of the system.
|
|
The physical design is more
complex when data are distributed at different locations because the
performances is effected by their communication media through put.
|
|
Implementation and
loading:
|
|
In this implementation phase, you
must address about
|
|
1. Performance
|
|
2. Security
|
|
3. Backup &
Recovery methods
|
|
4. Integrity
|
|
5. Company
standard
|
|
Performance:
|
|
Performance is an important factor
in DB implementation performance evaluation is rendered more difficult
because there is no standard measurements and thus it varies according to the
hardware, software environment used. The DB size also effects database
performance.
|
|
Security :
|
|
DB stored in the DB must be
protected from access by unauthorized users. Hence you must provide.
|
|
®
Physical security
|
|
®
Password security
|
|
®
Access rights
|
|
®
Audit trails
|
|
®
Data encryption &
|
|
®
Disc less workstation
|
|
Backup and
recovery:
|
|
The timely data availability is
critical and crucial step for almost
every data base. The DB can be subjected to database loss through unintended
data deletion powers outages etc. There fore the data backup and recovery
procedures create a value, by following allowing the DB to ensure the
availability of consistent data.
|
|
The DB vendors encourage the user
fault tolerant component such as ups (uninterested power supply), RAID
(redundant array of independent discs), external storage devices, clustered
servers etc., to ensure the continuous operations of the DB incase of
hardware failures. Some DBMS provide automatic DB backup to its permanent
storage devices such as hard discs, magnetic tapes & external storage
media such as DVD’s pen drives etc .
|
|
The DB backup’s can be:
|
|
®
Full backup of database
|
|
®
Last modification of the database
|
|
®
Transaction log backup etc.
|
|
Each stored in a secured place
& it is protected against dangers such as fire, flood, earthquakes &
theft and by other potential calamities.
|
|
Integrity:
|
|
Data integrity is a result of
property implemented data management policies Testing and evaluation.
|
|
When the data have been loaded in
the database after installation, the DB administration tests and fine tunes
the DB for performance, integrity, concurrent access, security constraints
etc.
|
|
This phase occurs in parallel with
the application programming.
|
|
The DB programmer us DB too’s
during coding of the program such as screen generators, menu generators,
report generators etc.,
|
|
If the DB implementation fails,
the DB designer must consider to review back.
|
|
®
Performance related issues
|
|
®
DBMS configuration parameters
|
|
®
Modify the physical design
|
|
®
Modify the logical design and
|
|
®
Update/ change DBMS software & hardware plat form
|
|
Operations:
|
|
Once the DB passed the evaluation
stage it is considered to be operational. The beginning of operational phase
is the process of system evaluation. When the end users, management & the
application programs entered into system operational phase then DB designer
must concentrate on
|
|
(a) The problems
that could not have been for seen during the testing phase.
|
|
(b) The serious
problems occurred in the system
|
|
(c) Minor,
annoyances, if any….. soon to provide alternative solution. Thus the
operation phase lead to maintenance & evaluation
|
|
Maintenance and
evaluation:
|
|
The DBA must prepare to perform
routine maintenance activities periodically with in the DB environment it
considers about
|
|
®
Preventive maintenance (backup)
|
|
®
Corrective maintenance
|
|
®
Adaptive maintenance
|
|
®
Access permissions
|
|
® Periodic
security etc.
|
|
Therefore, the likelihood of new
information requirements, additional demand of report quarries, the for mate
of reports & enhancement of application programs required on the demand
of user for possible minor changes in the DB must be done. These changes can
be easily implemented when the DB design is flexible and all documentation is
upto data & online.
|