Skip to main content

References to DBMS Concepts

Many of you may have some concern on Basics of DBMS and about the definitions of R-DBMS, H-DBMS and N-DBMS. Some of you might have studied the concepts little different than the one I have defined on my site, but nevertheless definitions and concepts(DBMS) on my site are simple and easy to understand which are explained at a very basic level. Am collating some links which will provide similar and more detailed definitions and insight on DBMS concepts.

DBMS and its history --
Types of DBMS --
Notes from Penn State University, USA --
Flat File Database --
Hierarchical DBMS --
Network DBMS --
Relational DBMS --
Database(Do not get confused with so much information, treat this link as a reference) --

Hope this clears the confusion in air.


rashmi dhiman said…
hello sir....i want a suggestion from u,can i do manual testing and QTP together...will it effect my study or any other loss???
Mithun Ashok said…
Hi Rashmi Dhiman,

If you want you can take do both Manual and QTP together only thing is you have to put in lot of effort and concentrate on both the topics.

It is suggested to take these courses one after the other so you get enough time to study.

TEJ said…
I'm looking for enotes of complete SQL notes.

Plz guide me as to which is the best book to refer!

With regards,
Tej G.K
Mithun Ashok said…
Hi Tej,

Follow the link below,

TEJ said…
Hi Mithun,

Thank you :)

With regards,
Tej G.K
TEJ said…
Hi Mithun,

I have small confusion between ROUND and TRUNC operator's.

Can you tel me the answers for the following qn's are right or wrong .
ROUND( 1742.471,-1) -> 1740
ROUND( 1742.471,-2) -> 1700
ROUND( 1742.471,-3) -> 2000

TRUNC( 1742.471,-1) -> 1740
TRUNC( 1742.471,-2) -> 1700
TRUNC( 1742.471,-3) -> 1000

Let me know if any answers wrong and explanat it plz.
Sir, Plz tell us that what would be the series of initial 5 questions that u would be asking in an inrterview ??
Plz tell us that what would be the initial 5 questions that u yould b asking in an interview on SQL .
Mithun Ashok said…
Hi Tej,

Execute these number functions and let me know if you have any queries.

Mithun Ashok said…
Hi Harish,

Will write an article on this gimme some time.

naresh n said…
hello sir........ i installed oracle that i entered password(system) and thre not asking any username by during installation....after completing sucessful installation its asking username also what can i do now...........?
Mithun Ashok said…
Hi Naresh,

Use scott as username and tiger as password.

Usha.V said…
Hi sir:) we have to display name,hire date,day of the week on which the emp started n order bt the day of the week starting with monday.
i wrote the query as:
SELECT ename,hiredate,to_char(hiredate,'DAY')as day
FROM emp
ORDER BY day=to_char(hiredate,'MONDAY');
but im nt getting the desired result. wht changes shld i do sir
Smruti said…
Hi Sir Please give the bellow questions answers.

What is the difference between trigger and constraint? Give more than five difference
Mithun Ashok said…
Hi Usha,

Refer to the article below,

Sorting by day of the week

Mithun Ashok said…
Hi Smruti,

Triggers are used to execute some procedure in case of database events.

Constraint are the restrictions that you can have on each column.

vamshi said…
hii sir, i have to learn some basics of pl/Sql and oracle apps for that what all is the basic knowledge required and can u mail me some useful material for this since i din't find in this site
wish you a very very happy deepawali sir.....
Uday Bhadauria said…
wish you a very very happy deepawali sir....
Amit Jha said…
i found this on internet...hope it will be useful for you...""
Unknown said…
Sir i am confuse about DBMS and RDBMS.Please tell me the different
Unknown said…
Mithun sir u are awesome, awesome teaching, interactive blog... great
saket singh said…
sir somehow meanwhile installation sql plus i missed unlocking in the username & password field what should i enter to access the s/w.......plz recommend me some suggestions

Popular posts from this blog

SQL Interview Questions on Subqueries

SUB Queries:
1. List the employees working in research department 2. List employees who are located in New York and Chicago
3. Display the department name in which ANALYSTS are working
4. Display employees who are reporting to JONES
5. Display all the employees who are reporting to Jones Manager
6. Display all the managers in SALES and ACCOUNTING department
7. Display all the employee names in Research and Sales Department who are having at least 1 person reporting to them
8. Display all employees who do not have any reportees
9. List employees who are having at least 2 reporting
10. List the department names which are having more than 5 employees
11. List department name having at-least 3 salesman
12. List employees from research and accounting having at-least 2 reporting
13. Display second max salary
14. Display 4th max salary
15. Display 5th max salary  -- Answer for nth Max Salary
Co-Related Subqueries:
16. Write a query to get 4th max salary from EMP table
17. Write a query to get 2nd…

Basics of RDBMS

Small set of information becomes data, this set of information helps make decision. Data is always some useful information.

Place where you store the data. Database represents some aspect of the real world called "miniworld". A database is designed, built and populated with data for a specific purpose. It has intended group of users and some preconceived applications in which these users are interested.

In other words, a database has some source from which data is derived, some degree of interaction with events in the real world and an audience that is actively interested in the contents of the database.

Database can also be defined as collection of one or more tables.

Ex: Mobile, human brain etc

DBMS (Database Management System)
Is a program that stores retrieves and modifies data in the database on request.

Study of different techniques of design, development and maintenance of the database

Types of DBMS
These types are based upon their management of database s…

Answers for SQL Functions

1. SQL> SELECT empno, ename FROM emp WHERE Length(ename) = 4;

2. SQL> SELECT empno, ename, job FROM emp where Length(job)=7;

3. SQL> SELECT Length('qspiders') - Length(replace('qspiders','s','')) FROM dual;

4. SQL>  SELECT empno, ename, job FROM emp WHERE Instr(job,'MAN') >0;

5. SQL> SELECT empno, ename, job FROM emp WHERE Instr(job, 'MAN') =1;

6. SQL> SELECT empno, ename, job FROM emp WHERE (Length(ename) - Length(Replace(ename, 'L',''))) = 1;

7. SQL> SELECT * FROM dept WHERE Instr(dname,'O') > 0;

8. SQL> SELECT Concat(ename,' working as a ') || Concat(job, ' earns ') || Concat(sal, '  in ') || Conc
at('dept ',deptno) AS text from emp;


SQL> SELECT Concat(Concat(Concat(Concat(Concat(Concat(Concat(ename,' working as a '), job),' earns '), sal),'  in '),'dept '), deptno) AS text FROM emp;

9. SQL> SELECT empno, ename…