Deprecated: mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in /home/lsp4you/public_html/connect.php on line 2 LSP4YOU - Learner's Support Publications
DBMS BCA Unit-5 Transaction - Definition Transaction - Examples COMMIT and ROLLBACK Properties of a Transaction States of Transactions The Concurrent Transactions Transactions - Lost Updates Transactions - Unrepeatable Reads Transactions - Dirty Reads Transactions - Inconsistent Analysis Serialisable Schedule Serial and Interleaved Schedule Precedence Graph Algorithm Precedence Graph Construction Non Serializable Schedule Locking Protocol Locks and Types of Locks Binary Locks Multiple-Mode Locks Shared and Exclusive Locks Two Phase Locking (2PL) Types of Two Phase Locking Database Security Goals Types of Database Security Threats to Databases Database Security & Authorization Subsystem Discretionary Security Mechanisms Mandatory Security Mechanisms Control Measures Access Control Inference Control Flow Control Data Encryption Database Security and the DBA DBA - Privileged Commands DBA Role Access Control, User Accounts and Database Audits System Log Database Audit Audit Trail Sensitive Data and Types of Disclosures Sensitive Data - Classification Factors Factors - Data is Safe Discretionary Access Control in a Database Account Level Privileges Relation Level Privileges Access Matrix Model Privileges on Relations


Transaction - Definition

Transaction is an action or series of actions, carried out by user or application, which accesses or changes contents of database.
  • A transaction is defined as the unit of work in a database system.
  • Application program is series of transactions with non-database processing in between.
  • Transforms database from one consistent state to another, although consistency may be violated during transaction.
Database systems that deal with a large number of transactions are also termed as transaction processing systems. Transaction is a unit of data processing.

E.g.:- Transactions at a Bank may be:
  • Withdrawal or deposit of money.
  • Transfer of money from A's account to B's account.
A transaction would involve manipulation of one or more data values in a database. Thus, it may require reading and writing of database value.