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?

ER diagrams, explain exhaustively the problems associated with ER diagrams....

explain exhaustively the problems associated with ER diagrams. include illustrations in your answer

Illustrate the deployment diagram, Illustrate the Deployment Diagram A...

Illustrate the Deployment Diagram A deployment diagram shows all nodes on network, their processor execution and interconnections. In a dynamic model, this is used to represen

A distributed transaction, A Distributed Transaction Let us demonstrate...

A Distributed Transaction Let us demonstrate the concept of a distributed transaction by considering a banking system having of three branches located in 3 different cities. Ev

What is primary index, Primary Index In primary index, there is a one-t...

Primary Index In primary index, there is a one-to-one relationship among the entries in the index table and the records in the major table. Primary index can be of two types:

Incident report to the database, The Form input elements are:           ...

The Form input elements are:             Reporter name                                                text type input             Password

Explain the fourth normal form, Fourth Normal Form (4NF) When attribut...

Fourth Normal Form (4NF) When attributes in a relation have multi-valued dependency, further Normalization to 4NF and 5NF are needed. Let us first find out what multi-valued d

Explain the recoverable schedule, Explain the Recoverable Schedule A r...

Explain the Recoverable Schedule A recoverable schedule is one in which for each pair of transactions Ti and Tj such that Tj reads a data item formerly written by Ti, the comm

Case snerio, each publisher has uniqe name a mial addrs are also kept on ea...

each publisher has uniqe name a mial addrs are also kept on each pubisher.a publisher publish one book.a book publish y one publisher.book identified by isbn.each book writn by one

What is the difference between a key and a superkey, What is the difference...

What is the difference between a key and a superkey? Key - A key a single attribute or a combination of two or more attributes of an entity set which is used to identify one

Create an entity relationship diagram, Cyber Transit Ltd keeps up-to-date i...

Cyber Transit Ltd keeps up-to-date information on the processing and current position of each dispatched item. Dispatched items are the main concern of the Cyber Transit product tr

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