For example, when a new record (representing a new worker) is added to the employees table, new records should also be created in the tables of the taxes, vacations and salaries.

Triggers can also be used to log historical data, for example to keep track of employees' previous salaries.

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Oracle trigger inserting or updating Chat de sexo portugueses

These trigger types are referred to as "Schema-level triggers". Performing conditional actions in triggers (or testing data following modification) is done through accessing the temporary Inserted and Deleted tables. The following functionality in SQL:2003 was previously not implemented in Postgre SQL: Firebird supports multiple row-level, BEFORE or AFTER, INSERT, UPDATE, DELETE (or any combination thereof) triggers per table, where they are always "in addition to" the default table changes, and the order of the triggers relative to each other can be specified where it would otherwise be ambiguous (POSITION clause.) Triggers may also exist on views, where they are always "instead of" triggers, replacing the default updatable view logic.

(Before version 2.1, triggers on views deemed updatable would run in addition to the default logic.) Firebird does not raise mutating table exceptions (like Oracle), and triggers will by default both nest and recurse as required (SQL Server allows nesting but not recursion, by default.) Firebird's triggers use NEW and OLD context variables (not Inserted and Deleted tables,) and provide UPDATING, INSERTING, and DELETING flags to indicate the current usage of the trigger.

The MERGE statement is designed to combine multiple operations to reduce the complexity of mixed insert and update operations.

MERGE allows you to avoid multiple INSERT, UPDATE, and DELETE DML statements by combining the operations into a single statement.

Let us now perform one more DML operation on the CUSTOMERS table.

sal_diff); END; / Because this is a new record, old salary is not available and the above result comes as null.

Say you would like to take transformed data and use it to update our dimension table.

In the past, we'd have accomplished this by a combination of INSERT and UPDATE statements, but starting with Oracle we've now got the Oracle MERGE command which does this in one step.

A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database.