How can you handle advanced exceptions in PL/SQL? Provide a scenario.

In PL/SQL (Procedural Language/Structured Query Language), handling advanced exceptions involves capturing specific error conditions and implementing customized error handling logic to deal with those exceptions. Advanced exception handling allows developers to handle exceptions that go beyond the standard error handling provided by PL/SQL. Let's discuss how you can handle advanced exceptions in PL/SQL and provide a scenario to illustrate its usage.

1. Handling Advanced Exceptions:

* PL/SQL provides a mechanism to handle exceptions through the use of the `EXCEPTION` block. The `EXCEPTION` block allows you to specify exception handlers that catch specific exceptions and handle them accordingly.
* Advanced exception handling involves the use of various exception handling techniques, such as nested blocks, user-defined exceptions, and exception propagation.
* By using advanced exception handling techniques, you can create more robust and targeted error handling mechanisms to deal with specific error conditions that may occur during program execution.
2. Scenario: Handling a Specific Error Condition:
Let's consider a scenario where you want to handle a specific error condition related to a database table. Suppose you have a PL/SQL procedure that performs an insert operation into a table. However, there is a requirement to handle a unique constraint violation error (ORA-00001) specifically, and perform a specific action when this exception occurs.

```
sql`DECLARE
unique_constraint_violation EXCEPTION;
PRAGMA EXCEPTION_INIT(unique_constraint_violation, -1); -- Associating the exception with the specific error code
BEGIN
-- Perform the insert operation
INSERT INTO employees (employee_id, employee_name) VALUES (101, 'John Doe');

EXCEPTION
WHEN unique_constraint_violation THEN
-- Customized handling for unique constraint violation error
DBMS_OUTPUT.PUT_LINE('The employee with ID 101 already exists in the database.');
-- Perform additional error handling or corrective actions here
END;
/`
```
In this scenario, the `unique_constraint_violation` exception is defined as a user-defined exception and associated with the error code (-1) that represents the unique constraint violation error. Within the `EXCEPTION` block, the specific exception handler is defined for `unique_constraint_violation`, which handles the unique constraint violation error by displaying a custom message and performing any additional error handling or corrective actions required.

By using advanced exception handling techniques like this, you can handle specific error conditions gracefully and take appropriate actions based on the nature of the exception. This allows for more precise error management and tailored responses to exceptional situations within your PL/SQL code.

It's important to note that in addition to handling advanced exceptions, you should also consider proper logging and error reporting mechanisms to capture and track exceptions, allowing for efficient troubleshooting and maintenance of your PL/SQL applications.