A view is a virtual table that is defined based on the result set of an SQL statement. It allows data to be queried from tables without exposing the actual base tables. The key differences between a view and base relation are that a view contains virtual data while a base relation contains physical data, views provide security while base relations do not, and modifications can generally be made to base relations but not views.

1. What is view? Discuss the difference between a view and a base relation. 5M
View:
1. A view is defined as a database object that allows us to create a virtual table in the database.
2. View is defined to hide complexity of query from user.
3. The table on which view is defined is called as base table.
4. There are two types of view: simple view and complex view.
5. Simple view allows DML operations.
6. In simple view views base on only one table and in complex view views base on more than
one table.
7. Complex view has join and grouping conditions.
8. Simple view has simple SQL conditions.
Difference between a view and a base relation:
No. Views Base relation
1 This is one type of relation which is not a
part of the physical database.
A base relation is a relation that is not a
derived relation. It consists of virtual data.
2 It has no direct or physical relation with
the database.
It has physical relation with the database.
3 Views can be used to provide security
mechanism.
Base relation does not provide security.
4 Modification through a view generally not
permitted.
Modification may be done with a base
relation.
5 A view is query over one or more base
relation.
A base relation contains data.
6 Views are dependent on base tables. Base tables are not dependent on views.
7 Using views complex query can be solved. Using base tables complex query cannot be
solved.
ACID properties 5M
ACID stands for Atomicity, Consistency, Isolation and Durability.
A. Atomicity:
1. The atomicity property identifies that the transaction is atomic.
2. Atomic transaction means transaction is fully completed or not started.

2. 3. If any part of the transaction fails, the entire transaction fails and the state of the database
remains unchanged.
4. If transaction unable to complete all the steps, then the system is returned to the state
before the transaction was started.
5. An example of atomic transaction is an account transfer transaction. The money is removed
from account A and added into account B.
If an error occurred after removing amount from account A, then the transaction processing
system will put that amount back to account A. that is system returned in its original state. This
is known as rollback.
B. Consistency:
1.Consistency property ensures that database remains in a consistent state before the start of
the transaction and after execution of transaction.
2. All the changes to the systemwill have been made properly and transaction will be in a valid
state.
3. If any error occurred then any changes made to the system will be automatically rolled back
to the state before transaction was started.
4. The systemwill be in a consistent state.
5. An example of account transfer transaction. The systemis in consistent state if the total of all
accounts is constant. If any error occurs and the money is removed from account A and not
added to account B, then the total in both account will change and it will became the value
before transaction was started.
By rolling back the removal from account A, the total will again what it should be and the
system back in a consistent state.
C. Isolation:
1. When a transaction runs in isolation, it appears to be the only action that the system is
carrying out at one time.
2. If there are two transactions performing same function at the same time, isolation ensures
that each transaction thinks it has exclusive use of the system.
3. If the transaction was not running in isolation, it can access data from system that may not
be consistent.

3. 4. By providing transaction isolation this will prevent from happening.
5. Depending on the concurrency control method, the effect of an incomplete transaction will
not be visible to another transaction.
D. Durability:
1. A transaction is durable after it completed successfully.
2. All the changes made to the system after completion of transaction are permanent.
3. Once the transaction committed successfully it will remain constant if there is power loss
crashes or any errors.
4. There are safeguards to prevent the loss of information in the case of system failure.
5. The concept of durability allows the developer to know that a completed transaction is a
permanent part of the system.
Difference between static SQL and dynamic SQL.5M
No. Static SQL Dynamic SQL
1 In static SQL, SQL statements are compiled
at compile time.
In dynamic SQL, SQL statements are
compiled at run time.
2 SQL query parsing, validation and
optimization are done at compile time.
SQL query parsing, validation and
optimization are done at run time.
3 It is generally used for situations where
data is distributed uniformly.
It is generally used for situations where data
is distributed non-uniformly.
4 Execute immediate and executes
statements are not used.
Execute immediate and execute statements
are used.
5 Static SQL is less flexible. Dynamic SQL is more flexible.
6 Static SQL is more efficient. Dynamic SQL is less efficient.
7 It is also known as embedded SQL. It is also known as interactive SQL.
8 Static SQL is static in nature. Dynamic SQL is dynamic in nature.
Difference between OLTP and OLAP. 5/10M
No. OLTP OLAP
1 OLTP stands for online transaction
processing.
OLAP stands for online analytical processing.
2 OLTP is characterized by large number of
short online transactions.
OLAP is characterized by low volume of
transactions.
3 OLTP are the original source of the data. OLAP data comes from the various OLTP
databases.
4 OLTP is application oriented. OLAP is subject oriented.

4. 5 OLTP is simple and short transaction. OLAP is complex query transaction.
6 Generally ER modeling is used to design
OLTP.
Dimensional modeling is used to design
OLAP.
7 OLTP is transaction oriented. OLAP is analysis oriented.
8 OLTP applications are used in database
management system.
OLAP applications are used in data
warehouses.
9 In OLTP system database size is 100MB to
GB.
In OLAP systemdatabase size is 100GB to
TB.
10 Data present in OLTP system is current
data.
Data present in OLAP systemis historic data.
11 OLTP system gives access to read or write
data.
OLAP system gives access to read data.
12 Data consists in OLTP systemis operational
processing data.
Data consists in OLAP system is
informational processing data.
13 Purpose of OLTP data is to control and run
fundamental business tasks.
Purpose of OLAP data is to help with
planning, problem solving and decision
support.
14 Processing speed in OLTP system is very
fast as compare to OLAP system.
Processing speed in OLAP systemis depends
on the amount of data involved.
15 Database design in OLTP system is highly
normalized with many tables.
Database design in OLAP systemis de-
normalized with fewer tables.
16 OLTP database schema is used to store
transactional databases.
OLAP database multidimensional schema is
used to store aggregated and historical
data.
Note on SQL injection. 5M
1. SQL injection is malfunction program used to hack databases.
2. SQL injection is a technique used for code injection which exploits security in the database
application programs.
3. Such SQL vulnerabilities are occurred when user input are not strongly checked.
4. SQL injection is one of the most common application layer attack technique used for
extracting valuable data from the databases.
5. SQL injection attacks:
i. Incorrectly filtered escape characters
ii. Incorrect type handling
iii. Vulnerabilities in database server

5. iv. Blind SQL injection
v. Conditional responses
vi. Conditional errors
vii. Time delays
6. Incorrectly filtered escape characters:
It occurs when user input is not properly filtered.
7. Incorrect type handling:
It occurs when a data field is not strongly typed checked for constraint.
8. Vulnerabilities in database server:
It occurs due to problem in server software.
9. Blind SQL injection:
This attack is used when a web application is vulnerable to an SQL injection but not visiblr to
the attacker.
10 Conditional responses:
This SQL injection evaluates a logical statement on an ordinary application screen.
11. Conditional errors:
This type of blind SQL injection attack causes some error.
12. Time delays:
Time delay is type of blind SQL injection. It causes to query to take infinite time to execute a
query.
List types of transparencies in distributed database and explain any one in detail. 5m
Types of transparencies in distributed databases:
a. Distribution/Network transparency
b. Fragmentation transparency
c. Replication transparency

6. a. Distribution/Network transparency:
1. In network transparency all internal network operations are hidden from the user.
2. Network transparency is divided into two transparencies:
i. Location transparency
ii. Naming transparency
i. Location transparency refers to task performed by user is independent of the location of data
and the location of the system.
ii. Naming transparency states that once a name is specified, these objects can be accessed
unambiguously.
3.
b. Fragmentation transparency:
1. The process of decomposing database into smaller multiple units is called as fragmentation
transparency.
2. In this fragmentation user accesses the data as like normal non fragmented data.
3.

7. c. Replication transparency:
1. Copy of data at multiple sites and location for better performance and availability is called as
replication transparency.
2. Replication transparency makes user unaware of the existence of copies of data.
3.

8. Explain SQL trigger with example. 5M/10M
1. The SQL CREATE TRIGGER statement provides a way for database management systemto
actively control, monitor and manage a group of table whenever an insert, update or delete
operation is performed.
2. The statement specified in SQL trigger is executed each time an SQL insert, update, delete
operation is performed.
3. An SQL trigger may call stored procedure or an additional user defined functions to perform
additional processing when the trigger is executed.
4. Triggers are stored in database as a simple database object.
5. A database that has asset of associated trigger called as active database.
6. An SQL trigger cannot directly called from an application. Instead, an SQL trigger is invoked
by the database management systemupon the execution of triggering insert, update or delete
operation.
7. SQL trigger is invoked by the database management system when the SQL table that the
trigger is defined on, is modified.
8. Components of trigger: SQL trigger consist of following components (ECA).
i. Event: Performs insert, update or delete operations.
ii. Condition: A condition that must be satisfied for execution of trigger.
iii. Action: This code executed when trigger condition is satisfied.
9. Types of trigger: There are two types of triggers: Row level trigger and Statement level
trigger.
i. Row level trigger fixed each time when the table is affected by trigger statement.
ii. Statement level trigger executes only once if no rows are affected by trigger statement.
10. Operations on trigger:
i. Data dictionary for trigger:
select * from user trigger where trigger_name=’<trigger_name>’;
ii. Dropping trigger:

9. drop trigger <trigger_name>;
iii. Disabling trigger:
alert trigger <trigger_name> {disable|enable};
11. Parameters used in trigger: CREATE, REPLACE, BEFORE, AFTER, INSERT, UPDATE, DELETE,
REFERENCING, FOR EACH ROW, WHEN, <TRIGGER_NAME>, <TRIGGER_CODE>, EXCEPTION.
12. Trigger syntax:
Create [OR replace] trigger <trigger_name>
[<ENABLE|DISABLE>]
<BEFORE|AFTER>
<INSERT|UPDATE|DELETE>
[of <column_name_list>]
ON <table_name>
[referencing new as <synonym> old as <synonym>]
[for each row][when (<trigger_condition>)]
declare
Variable definitions>
BEGIN
<trigger_code>
Exception
<exception_clauses>
ENN<trigger_name>;
13. Examples of trigger:
i.
create table source (source_id int IDENTITY, source_desc varchar(10))

10. go
create trigger tr_source_insert
ON source
FOR insert
AS
PRINT GETDATE()
Go
Insert source (source_desc) values(“Test 1”):
ii.
create table CS (student_ID int IDENTITY, student_desc varchar(90))
go
create trigger CSAutoRecruit
after insert on student
referencing new as newstudent
when(newstudent.GPA>3.0)
insert into take values(newstudent.SID,’CS’)
FOR EACH ROW;