Database Transactions

A database transaction consists of one of the following :

• DML statements that constitute one consistent change to the data
• One DDL statement
• One data control language (DCL) statement
• PostgreSQL commit automatically when you perform a transaction.
• You can explicitly start a transaction using BEGIN keyword.
• Transaction that are explicitly started using BEGIN end with one of the following events:
  
  • A COMMIT or ROLLBACK statement is issued.
  • The user exits psql.
  • The system crashes.

Advantages of COMMIT and ROLLBACK Statements :
With COMMIT and ROLLBACK statements, you can :

• Ensure data consistency
• Preview data changes before making changes permanent
• Group logically related operations

Controlling Transactions :