Transaction concept in DBMS

Data Base Management System



Transaction

, Transaction
• A transaction is a logical unit of work, of database
processing that includes one or more database
access operations(insertion, deletion, modification)
or retrieval operation.

• An action or series of actions that is carried out by a
singe user or application program to perform
operation for accessing the contents of database.

, Transaction
• A transaction must be completed or aborted.

• A transaction is a set of logically related operations.

• For example, you are transferring money from your bank account to
your friend’s account, the set of operations would be like this:

• Simple Transaction Execution:
1. Read your account balance

2. Deduct the amount from your balance

3. Write the remaining balance to your account

4. Read your friend’s account balance

5. Add the amount to his account balance

6. Write the new updated balance to his account

, Transaction
• A transaction is a sequence of READ and WRITE
actions that are grouped together to database
access.
Initial State
Previous X=8000
balance

Salary
database X=X-1000 Read -> Modify -> Write


n ce
la
B a ew
N
X=7000 Final State