Transcript Database Designers

DBMS USERS
TOPICS TO BE DISCUSSED……………
Actors on the scene:
Persons whose job involves use of a large database are:
(a) Database administrator
(b) Database designers
(c) End Users
(d) System Analyst
Workers behind the scene
Persons whose job involves design, development, operation and maintenance
of DBMS software are:
(a) DBMS designers and implementers
(b) Tool Developers
(c) Operator and maintenance personal
Database Administrator (DBA)
Database Administrator is a person or group of persons responsible for
overall control of database system. All the activities of database system are
controlled by DBA. Some of the main activities are as follows:
Deciding the information contents of database system: It is the DBA
who decides information contents of database system.DBA decides fields,
type of fields and range of values that can be stored in fields. In other
words DBA decides schema of database
Deciding hardware device to be used: It is the database administrator’s
job to decide which hardware device will be most suitable for current
database applications. Trade off between cost and efficiency is perfromed
by DBA to decide the storage device.
Deciding the users and data to be used by users: It is the DBA who
decides users of the database system.DBA also decides which information
contents are to be used by a particular user. This is performed by writing
subschema.
Deciding the back-up and recovery method: to avoid accidental loss of
data back-up of data is maintained on regular intervals. It is the DBA who
decides which data is to be backed up and when i.e. amount of data and
frequency of data decided by DBA. If data is loosed then it is the DBA
who recover data from existing back-up.
Deciding the validation checks on the data: It is the DBA who decides
which checks are to be maintained on existing data in database system.
Standards to be maintained are also decided by DBA.
Monitoring performance and responding to changing requirements:
The DBA is responsible for organizing the systems to get the performance
that is best for the enterprise and for making the appropriate adjustment
and requirements change.
Database Designers
Database designers task is undertaken before the database is actually
implemented. Responsibilities of Database designers are:
1.
Schema definition: the creation of original database schema.
2.
Storage structure and access method definition: it includes writing a set
of definitions translated by the data storage and definition language
compiler.
3.
Schema and physical organization Modifications: it includeswriting a set
of definitions to generate modifications to appropriate internal system
tables
Hence, database Designers are responsible for:
1.
Identifying the data to be stored in the database
2.
Choosing appropriate structure to represent and store this data.
End Users
End users are the users, who use the applications developed. End users need
not know about the working, database design, the access mechanism etc.
They just use the system to get their task done. End users are of two types:
a) Direct users
b) Indirect users
a) Direct users: Direct users are the users who see the computer, database system
directly, by following instructions provided in the user interface. They interact
using the application programs already developed, for getting the desired result.
E.g. People at railway reservation counters, who directly interact with database.
b) Indirect users: Indirect users are those users, who desire benefit form the work
of DBMS indirectly. They use the outputs generated by the programs, for
decision making or any other purpose. They are just concerned with the output
and are not bothered about the programming part.
System Analyst
System analysts determine the requirements of end users. He also analyses
the user requirement so that the DBMS data fields can be selected to fulfill
user needs. This requirements include the number of fields, size, type etc.
Once analyzing all these requirement he also uses the skill for coding so
that codes can be decided for efficient use of DBMS.
Application Programmers
These users write application programs to interact with the database.
Application programs can be written in some programming language such
a COBOL, PL/I, C++, JAVA or some higher level fourth generation
language. Such programs access the database by issuing the appropriate
request, typically a SQL statement to DBMS.
Functions of Application Programmer
Determine the requirements of end users, especially naive and
parametric end users, and develop specifications for canned
transactions that meet these requirements
Application programmers implement these specifications as
programs; then they test, debug, document, and maintain these
canned transactions
DBMS Designers And Implementers
They perform tough and responsible job. The DBMS system designer
knows the hardware requirements of the system and through his analyzing
and designing capability, he produces an efficient system design for the
DBMS.
The DBMS system implementers are those who help for hardware
implementation of the entire system. They do not play role in software
implementation.
Tool Developers
Tool developers help to develop the software tools for the DBMS. It is their
job to provide complete management, help and other database creation and
maintenance tools for the DBMS.
Operators and Maintenance Personal
The operators, who know to operate the entire system, are fully responsible
for proper running and operation of hardware parts of complete system.
The
final job is the maintenance of machinery for the entire system. The
maintenance not only includes repair and proper working, it also includes the
up gradation of equipments as an when required. All of them are technical
people and they know how to maintain, operate and upgrade the system.
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