Craig Nelson's List: MySQL Triggers

"Once created trigger associated with a table, you can view the trigger by going directly to the folder which contains the trigger. Trigger is stored as plain text file in the database folder as follows: /data_folder/database_name/table_name.trg, with any plain text editor such as notepad you can view it. MySQL provides you another way to view the trigger by executing SQL statement:"

"Let’s start creating the first trigger in MySQL by following a simple scenario. In the sample database, we have employees table as follows:
Each time a employee wants change his/her last name, you want to keep track all of changes in another table. In order to do so you can create a new table called employees_audit to keep track the changes."

"MySQL finally supports one of the most important features of an enterprise database server which is called trigger since version 5.0.2. Trigger is implemented in MySQL by following the syntax of standard SQL:2003. When you create a trigger in MySQL, its definition stores in the file with extension .TRG in a database folder with specific name as follows:"

"SQL trigger is an SQL statements or a set of SQL statements which is stored to be activated or fired when an event associating with a database table occurs. The event can be any event including INSERT, UPDATE and DELETE. "