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REALSQLDatabase (SQLite)
Triggers and Views
Issue: 5.1 (September/October 2006)
Author: Paul Lefebvre
Article Description: No description available.
Article Length (in bytes): 3,440
Starting Page Number: 38
RBD Number: 5115
Resource File(s): None
Related Link(s): None
Known Limitations: None
Excerpt of article text...
The features of SQLite that we'll be looking at this time are Triggers and Views. These are two fairly advanced database concepts, so they won't be something that you will need all the time. However, it is important to know about them and to keep them in mind as a possible way to simplify any databases you are creating.
Triggers
A database trigger is essentially code that lives on the database and that is run automatically (or is "triggered") when a specific action occurs. Triggers can be a useful way to enforce data integrity rules directly on the database. This can prevent bad data from ever being inserted into a database, even by someone who doesn't use your application.
A trigger is associated to a table and runs automatically when a specific action occurs on a table, such as inserting, updating or deleting data. The trigger contains SQL commands to run when the event occurs. Some reasons for triggers include:
You delete a row from a child table and you want to make sure that the foreign key in the parent table is set to NULL.
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