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?

What do you understand by a view, What do you understand by a view? What do...

What do you understand by a view? What does WITH CHECK OPTION clause for a view do? - A view is a virtual table which comprises fields from one or more real tables. - It is

When are two schedules said to be view equivalent, When are two schedules s...

When are two schedules said to be view equivalent?     Ans: Two schedules that is denoted as S and S' are said to be view equivalent if the subsequent three conditions are met

NORRMALIZATION, Home based assignment Consider an ORDER table with the foll...

Home based assignment Consider an ORDER table with the following attributes: • Order Number (ONo),Customer Number (CNo),Customer Name (CNa),Item Number (INo),Unit Price (UP), Quant

Benefits abd drawback of hashed file organisation, Benefits of Hashed file ...

Benefits of Hashed file Organisation 1.      Insertion or search on hash-key is quick. 2.      Best if equality search is required on hash-key. Drawbacks of Hashed file

Entity relationship diagram, Ask questApollo Hospitals (AH) is a popular me...

Ask questApollo Hospitals (AH) is a popular medical service provider in Oman. AH wants to automate its business functions into an information system. The proposed information syst

Why a report generator is used, Why a report generator is used ? Report...

Why a report generator is used ? Report generator is used for print files on paper.

When it is better to use files than a dbms, When It is better to use files ...

When It is better to use files than a DBMS? It is better to use files than a DBMS when Multiple users wish to access the data.

Compare the efficiency of the two mining processes, Consider the following ...

Consider the following database containing five transactions. Let min_sup = 60%. Mine all frequent itemsets using Apriori and FP-growth algorithm. Compare the efficiency of the t

Modelling and normalisation, Task Part A. Create an ERD from a business pro...

Task Part A. Create an ERD from a business problem. (50 marks) Read the following problem and complete the tasks listed below. THE ABS Blood Bank Australian Blood Services (ABS) i

What is the full form of odbc, What is the full form of ODBC ? ODBC stand...

What is the full form of ODBC ? ODBC stands for Open Database Connectivity.

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