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CREATE TRIGGER HistoryTable ON OriginalTable FOR INSERT, DELETE, UPDATE AS DECLARE @ Now DATETIME SET @ Now = GETDATE /* deleting section */ UPDATE HistoryTable SET EndDate = @ Now WHERE EndDate IS NULL AND Column1 = OLD.
The following is an Oracle syntax example of a row level trigger that is called AFTER an update FOR EACH ROW affected. This trigger is called on an update to a phone book database. When the trigger is called it adds an entry into a separate table named phone_book_audit.
SQL statements are used to perform tasks such as insert data to a database, delete or update data in a database, or retrieve data from a database. Though database systems use SQL, they also have their own additional proprietary extensions that are usually only used on their system.
Stored procedures can also be invoked from a database trigger or a condition handler. For example, a stored procedure may be triggered by an insert on a specific table, or update of a specific field in a table, and the code inside the stored procedure would be executed.
For example, LAST_INSERT_ID() for MySQL. Using a unique combination of elements from the original SQL INSERT in a subsequent SELECT statement. Using a GUID in the SQL INSERT statement and retrieving it in a SELECT statement. Using the OUTPUT clause in the SQL INSERT statement for MS-SQL Server 2005 and MS-SQL Server 2008.
In this approach, triggers log events that happen to the transactional table into another queue table that can later be "played back". For example, imagine an Accounts table, when transactions are taken against this table, triggers would fire that would then store a history of the event or even the deltas into a separate queue table.
Perhaps expectations were way too high prior to the big launch. After all, a sophisticated and truly personalized AI in your phone, like in the film Her, is going to take more than just one update ...
A view update is done by key preservation. Some systems support the definition of INSTEAD OF triggers on views. This technique allows the definition of other logic for execution in place of an insert, update, or delete operation on the views. Thus database systems can implement data modifications based on read-only views.