Example of transaction? , Database Management System

Assignment Help:

Example:; transfers transfer_amount from x's account to y's account

; Supposes x&y both accounts exist

TRANSACTION (x, y, transfer_amount)

Start transaction

IF X AND Y exist then

READ x.balance

IF x.balance > transfer_amount THEN

x.balance = x.balance - transfer_amount

READ y.balance

y.balance = y.balance + transfer_amount

COMMIT

ELSE DISPLAY ("BALANCE IN X NOT OK") ROLLBACK

ELSE DISPLAY ("ACCOUNT X OR Y DOES NOT EXIST") End_transaction

Please note the use of 2 keywords here COMMIT and ROLLBACK. Commit makes sure that all the modifications made by transactions are made permanent. ROLLBACK ends the transactions and discards any change made by the transaction. Transactions have definite desirable properties. Let us see into those properties of a transaction.


Related Discussions:- Example of transaction?

Implementation of database, The ER diagram clearly showing the additional t...

The ER diagram clearly showing the additional tables you have implemented. SQL table creation scripts for the tables you have set up. SQL scripts showing the sample data you

Oracle, comparison of oracle RDBMS with MySQL

comparison of oracle RDBMS with MySQL

Create a er diagram to show customer accounts, Information about a bank is ...

Information about a bank is about customers and their account. Customer has a name, address that consists of house number, area and city, and one or more phone numbers. Account ha

Ideal data dictionary, An ideal data dictionary should have everything a DB...

An ideal data dictionary should have everything a DBA wants to know about the database. 1 Conceptual, External, and internal database descriptions. 2.    Descriptions of attr

Sources of utilities for a dbms, There are three main sources of utilities ...

There are three main sources of utilities and applications for a DBMS: a. Vendor applications and utilities are given for working with or maintaining the database, and generally

What is an object id, What is an object ID? Each class-derived table ha...

What is an object ID? Each class-derived table has an ID for primary key, one or more object IDs form primary key for association derived tables. An object ID is equivalent dat

Compare the nested-loop join and block-nested loop join, Compare the Nested...

Compare the Nested-loop join and block-nested loop join Ans: Nested  loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r   where b

Define the term e-government, Question: (a) Define the term e-Governme...

Question: (a) Define the term e-Government and briefly explain, using appropriate examples, the aspects it covers. (b) Give four reasons as to why a country should adopt e

Give concurrent sub states diagram for the classroom, Give Concurrent sub s...

Give Concurrent sub states diagram for the classroom and exam held. In Figure, simultaneous substrates have been taken. After passing Minor 1 test you could give Minor 2 test. T

Vertical fragmentation, Vertical Fragmentation- Vertical fragmentation grou...

Vertical Fragmentation- Vertical fragmentation groups together only those attributes in a relation that are used jointly by various important transactions. A vertical fragment is d

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd