Oracle Triggers Guide: Types & Uses

An Oracle trigger is a type of database object that automatically executes a predefined block of PL/SQL code when a specific data operation (such as insert, update, or delete) occurs. Triggers can be used to implement complex business logic, enforce data constraints, and maintain data consistency, among other functions.

Oracle triggers can be defined at the table level or row level, known as table triggers and row triggers respectively. Table triggers are fired on the entire table, while row triggers are fired on each individual row.

Triggers can be defined on multiple events, including INSERT, UPDATE, and DELETE events. When these events are triggered, the trigger will automatically execute pre-defined PL/SQL code.

Triggers can have two types of trigger times: BEFORE (executes before the data operation) and AFTER (executes after the data operation). BEFORE triggers can be used for data validation or modification before the data operation, while AFTER triggers can be used for post-processing after the data operation.

In the PL/SQL code of triggers, special keywords and variables such as :OLD and :NEW can be accessed. The :OLD keyword represents the old data value, while the :NEW keyword represents the new data value. These keywords and variables can be used for data manipulation and processing in triggers.

Triggers can be used to achieve various functions such as real-time calculations, data synchronization, data auditing, data constraints, and maintaining data consistency. Triggers are a powerful and flexible feature in Oracle databases that can help developers meet complex business requirements.