We have triggers in the report builder. A report trigger is a pl/sql block in which we can incorporate the business logic. If some input value failed according to the business rules then we can stop the process with out proceeding to the next step.

Always triggers returns a boolean. If it returs TRUE then the process takes the next step, if it returns FALSE then it stops the processing. So when a business rule gets failed you can return a FALSE after showing some message to the user using srw.message function.

This is handy to change the where clause, change the titles for the report based on the user's choice of input. We can change the order by clause based on user's selection in the parameter form. So at that time we have to use triggres to manipulate the order by clause before running the sql.
 

When you run a report it goes through the following processes.

• First Before Parameter Form Trigger executes
• then it shows the Parameter Form to users, after user enter the filter criteria
• then After Parameter Form Trigger executes
• then Before Report Trigger Executes
• then it executes the SQL for the report's data
• then it executes the between pages trigger in between each page
• then after processing all the pages it executes the after report trigger and it ends the process.

Before Parameter Form - Mostly you wont use this trigger.

After Parameter Form  --We use this trigger quite often

Before Report  --This is the most used trigger while developing reports.

Between Pages  -- We may never use this trigger

After Report  -- You may use this trigger if you are doing some DML operations to keep track of who ran this report etc etc for the audit purposes.