Transactions allow users to store and retrieve data through database instructions. A transaction represents the execution of a query and involves read/write operations on database objects. Transaction management ensures partial transactions do not leave the database in an inconsistent state. The key aspects of transactions are their ACID properties - Atomicity, Consistency, Isolation, and Durability. Atomicity means transactions are fully completed or not completed at all. Consistency requires the database remain consistent after a transaction. Isolation ensures transactions are isolated from each other. Durability means transaction changes persist after a system failure.

1. MCA, MSc(CS), PGDCA
Pratibha Rashmi

2.  User can store and retrieve data through various
sets of instruction. These sets of instructions do
several read and write operations on database
.These processes are denoted by a special term
“Transaction” in DBMS .“Transaction” in DBMS .
 Transaction is a basic unit of program execution.
Which possibly access and update the various
data item in a database, e.g. transferring money
to an account to another, withdraw, deposit etc..
 Transaction Management plays a crucial role in
DBMS . Partial transaction let the database in an
incosistency state, so they should be avoided .

3.  Object : The smallest Data item which is read or
updated by the Transaction .
 Transaction : is represented by the symbol T. It
is termed as the execution of query in DBMS .
 Read Operation : Read operation on particular
object is notated by symbol R (object-name) .
 Read Operation : Read operation on particular
object is notated by symbol R (object-name) .
 Write Operation : Write operation on particular
object is notated by symbol W (object-name) .
 Commit : Used to denote the successful
completion of one Transaction .
 Abort : Used to denote the unsuccessful
interrupted Transaction .

4.  Transaction Manager is responsible for scheduling
the Transactions and providing the safest path to
complete the task.
 There are properties that all transactions should
follow and possess. The four basic are in
combination termed as ACID properties. ACID
properties and its concepts of a transaction are
combination termed as ACID properties. ACID
properties and its concepts of a transaction are
put forwarded by Haerder and Reuter in the year
1983. The ACID has a full form and is as follows:
 ACID is an acronym for :
 A – Atomicity
 C – Consistency
 I – Isolation
 D – Durability

5.  Atomicity: This property states that either
all the operations of the transaction are
executed or none.
Transactions can be incomplete for three
kinds of reasons :
 Transactions can be aborted, or terminated Transactions can be aborted, or terminated
unsuccessfully.
 Due to system crash.
 Due to unexpected situations.
 Consistency: This property states that after
the execution of transaction the database
must be consistence.

6.  Isolation: In DBMS system, there are many
transaction may be executed simultaneously.
These transactions should be isolated to each
other .
To enforce this concept DBMS has to maintain
certain scheduling algorithms. One of the
scheduling algorithms used is Serial
SchedulingScheduling
 Durability: After the successful transaction
on the database, all the modifications must
be reflecting within the database even after
a system failure.

7.  Which of the following ensures the atomicity
of the transaction?
(A) Transaction management component of DBMS
(B) Application Programmer
(C) Concurrency control component of DBMS(C) Concurrency control component of DBMS
(D) Recovery management component of DBMS
 The part of a database management system
which ensures that the data remains in a
consistent state is
(A) authorization and integrity manager
(B) buffer manager
(C) transaction manager
(D) file manager

8.  Isolation of the transactions is ensured by
(A) Transaction management
(B) Application programmer
(C) Concurrency control
(D) Recovery management(D) Recovery management
 Which of the following is not a property of
transactions?
(A) Atomicity
(B) Concurrency
(C) Isolation
(D) Durability

9.  Q1. Define transaction and explain its
properties with suitable example.
 Q2. What is transaction. explain ACID
properties with suitable example.properties with suitable example.