Oracle Exception Handling Mechanism

1. Exception Handling
A warning and error in pl/SQL is called an exception. Exceptions include compilation exceptions and running exceptions.

2. Exception Classification
System exception
Custom exception

3. Abnormal Structure

Exception
When... then
..

4. Common System exceptions
System exception description
DUP_VAL_ON_INDEX violation and uniqueness constraints
NO_DATA_FOUND does not return a value in a select into statement.
TOO_MANY_ROWS returns too many rows
VALUE_ERROR an algorithm, conversion, truncation, or size constraint error occurs
Zero Division Error in ZERO_DEIIDE denominator
Eg:
Declare
Test varchar2 (20 );
Begin
Select name into test from depart where id = 'jjj ';
Dbms_output.put_line (test );
Exception
When NO_DATA_FOUND THEN
Dbms_output.put_line ('data does not exist! ');
End