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?

Data replication, Data Replication "If a relation R has its copies kept...

Data Replication "If a relation R has its copies kept at two or more sites, then it is considered replicated". But why do we replicate a relation? There are several advan

Mapping, external and internal mapping with examples

external and internal mapping with examples

Create a table for database transformation , Step 1 . Using Oracle, create ...

Step 1 . Using Oracle, create the tables identified in the preferred solution for Assignment 2. Technicians (ZipCode, TechnicianID, FirstName, LastName, Street, City, State, Home

Update anomaly-data redundancy, Update Anomaly : This anomaly is occurred d...

Update Anomaly : This anomaly is occurred due to data redundancy. Redundant information makes updates more complex since, for example, varying the name of the instructor of MCS-014

Erd, er diagram on cosmetics.

er diagram on cosmetics.

Data aggregation, Q.   Explain  data aggregatio n and discuss differen...

Q.   Explain  data aggregatio n and discuss different design constraints. Sol. Aggregation   One limitation of the E-R model is that it cannot express relationships amon

Design an algorithm to implement operations, Design an algorithm to impleme...

Design an algorithm to implement operations  Each and every operation specified in the functional model could be formulated as an algorithm. The algorithm indicates how operat

Discuss on transmission impairments, Question 1 Discuss on transmission im...

Question 1 Discuss on transmission impairments Question 2 What is framing? Question 3 Write a note on 10Base2 10Base- T Question 4 Explain the rev

What is recovery management component, What is recovery management componen...

What is recovery management component? Ensuring durability is the responsibility of a software component of the base system known as the recovery management component.

Explain the concept of qbe, Explain the concept of QBE? Query-by-exampl...

Explain the concept of QBE? Query-by-example represents a visual/graphical approach for accessing information in a database by the use of query templates called as skeleton tab

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