There are six general categories for database-related failures. Understanding what category a failure belongs in will help you to more quickly understand the nature of the recovery effort you need to use to reverse the effects of the failure and maintain a high level of availability and performance in your database. The six general categories of failures are as follows:
Statement A single database operation fails, such as a DML (Data Manipulation Language) statement— INSERT, UPDATE, and so on.
User process A single database connection fails.
Network A network component between the client and the database server fails, and the session is disconnected from the database.
User error An error message is ...