DBMS - Basics, Terms and Points to Remember
I am going to start
writing on Computer topics, starting with, what most you (the non-engineering
ones), consider as a difficult topic – DBMS.
Only because it
sounds so serious and technical doesn't actually mean it’s a tough topic to
understand. Trust me, when I first read the chapter, every thing sounded Greek
and Latin* to me, so, I re-read it couple of more times and I forgot what had
been so difficult!
So, what is DBMS? It
is Data Base Management System. Off course!
I’m sure all you know
the full form, but have you really ever given a thought to the words that make
up the full form – ‘cause that is where the entire secret lies in understanding
the core of this chapter!
Data – is any input
which has been processed. It can be in numeric, alphabetic or alphanumeric
form. Try to imagine data as physical files…the kind of dusty files found in
government offices.
This processed data
(or dusty files) needs to be stored and kept somewhere, so that when we need
them we can easily retrieve it.
But where do we keep
it? How do we keep it?
Don’t worry; the
computer experts have solved your problem by creating the ‘database’.
Database – is simply
a ‘place’ where all the data are collected and stored in an organized manner.
Think of it as a
collection of many steel racks, like the ones found in old government offices!
All the files/data are kept according to their serial numbers/file/folder names
(or any other identification style), and stored in the racks/database.
Management system –
In government officers, there are peons who are responsible for keeping the
files in the right place, bringing required files to the senior officers,
putting it back again after updating the files etc., this is nothing but the
system of file management in the office.
Similarly, in
computer’s database, it’s ‘management system’ is doing the work of the peon;
bring the required files, putting back in the right place, etc. but more
efficiently than a peon and faster too!!
I really do hope some
vapour-ish ideas are forming in your head about DBMS!
Thus, putting down
all our ideas in definition form – DBMS is a software,
(i) which helps a
user in creating a collection of records and information and storing them on
the computer in a systematic way (database),
(ii) it also helps in
organizing, sorting and retrieval of the records/information from the database,
when required by the user, to help the user in decision making (management
system).
DBMS MODEL
Benefits of DBMS:-
Faster storage and retrieval time
Accessing data is easy and fast
Data integrity(credibility of the data) and
security. In govt. offices, anyone can pick up any file! But DBMS requires
password authorization to access important files.
Backups and recovery are possible only in
digital world, hence today physical files are becoming extinct.
Points to remember in
DBMS
In DBMS data are stored in relational
model, using tables with rows and columns (remember the steel racks!).
There are two types of Data Manipulation
Languages (DML), Structured Query Language (SQL) and Data Definition Language
(DDL).
DML are computer languages also known as
query language, it is used for accessing and working on the data.
In other words, DML (SQL and DDL), are like
the languages people use, Hindi or English, in an office to give orders to the
peon!
Data redundancy – which means there are no
duplications of data. No multiple files of the same kind.
Data dictionary – is like a normal
dictionary, but containing metadata.
Metadata – contains information about all
the data in the DBMS.
The Keys – Primary key is used to identify
a particular or specific record (file). It is unique to a particular file.
Foreign Key makes a connection between a
component (field) in one table with a component identified by a primary key.
Relational database – is the kind of
database model, where there are logical connections between the various files,
which are kept in tables.
For example: In the given diagram, the
information is stored in tables (with rows and columns), in this particular
case in two relational tables.
Every column has a Field name (employee ID,
first name, last name, e-mail ID, Department ID and Department name).
The relation between the two tables is
created by the field ‘Department ID’, which connects the Employees name/ID/e-mail
to a particular Department like HR or software or accounts.
This is relational database, where a
relation is made between items of the database.
DBMS
That’s all folks.
I am hoping that DBMS
is no more vapour-ish but solid concrete! It can not get simpler than this!
Keep learning and
keep sharing the knowledge - that’s the best way to gain knowledge
