Question

1. Suppose that a database modification results in the execution of a trigger but that trigger generates another modification that happens to violate a primary-key constraint. What happens?

Answer 1

Please find the following answer for the given question here.

What is Trigger:

We can use triggers to perform a number of automatic actions to any table data tables when there is changes (like update, insert, delete) in any of the existing tables.

Triggers are automatic and it gets executed once for each SQL statement on modifying the database tables. Its also a special kind of stored procedure which gets executed when there is event in data base.

Syntax:

create trigger [triggerName] [after| before]  
{insert | update | delete}  
on [tableName]  
[for each row in table]  
[body  of the trigger]

Answer:

As we know triggers always ran as part of transaction,

When there is a failure in trigger and if we have "rollback transaction" then complete transaction will be rolled back and no modification/changes are made to the table.