Triggers are commonly used to supplement the built-in auditing features of Oracle. 
Although triggers can be written to record information similar to that recorded by the AUDIT command, 
triggers should be used only when more detailed audit information is required. For example, use triggers
to provide value-based auditing on a per-row basis for tables.

 Currently, four types of triggers exist in SQL Server, and the first two are the most commonly used:

• DDL triggers (auditing CREATE, ALTER, DROP and several system-defined stored procedures which perform DDL operations) are often used for administrative tasks like regulating and auditing database operations

• DML triggers – our focus will be on this type of trigger as they provide auditing of data changes. This type of audit triggers fires upon DML statements (like INSERT, UPDATE, and DELETE) as well on stored procedures that execute DML-like operations

• CLR triggers are a special type of auditing triggers that enables trigger techniques to be used directly within .NET languages, and they support SQL Server 2008 and above

• Logon triggers fire when a SQL Server LOGON event occurs. It can be used to track successful authentication and control and audit server sessions