Explain the Database Life Cycle (DBLC)?

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.