CBSE Class 12 Informatics Practices More RDBMS Assignment

More RDBMS(Relational Database Management System)

Q.1: What do you mean by DBMS and Transaction Management ?

Suppose Raunak's account number is 3246 and his aunt's account number is 5135. In order to process the cheque presented by Raunak, the following two SQL commands need to be executed on the database maintained by the bank:

UPDATE Savings SET balance = balance – 2000 WHERE account_no = 5135; For Aunt's account

UPDATE Savings SET balance = balance + 2000 WHERE account_no = 3246; For Raunak's account

The above two Updates should both take place. If the first Update takes place and there is a system failure, the first updation should be undone. Either both the updations should be done and if it is not possible for both the updations to be done, then no updation should be done.

Q. 2: What is a Transaction?

A Transaction is a unit of work that must be done in logical order and successfully as a group or not done at all. Unit of work means that a Transaction consists of different tasks - but together they are considered as one unit. Each transaction has a beginning and an end. If anything goes wrong in between the execution of transaction, the entire transaction (No matter to what extent has been done) should be cancelled. If it is successful, then the entire transaction should be saved to the database.

A transaction is a unit of work that must be done in logical order and successfully as a group or not done at all. 

In Raunak's case, both the updation statements constitute a transaction. Both are together treated as a single unit.

Q.3: how transactions are managed ?

 let us study the following 3 statements of SQL:

• START TRANSACTION statement

• COMMIT statement

• ROLLBACK statement

Please refer to attached file for CBSE Class 12 Informatics Practices More RDBMS Assignment