In PL/SQL, the user can catch certain runtime errors.
Exceptions can be internally defined by Oracle or the user.
Exceptions are used to handle errors that occur in your PL/SQL code.
A PL/SQL block contains an EXCEPTION block to handle exception.
There are three types of exceptions:
Predefined Oracle errors
Undefined Oracle errors
User-defined errors
The different parts of the exception.
Declare the exception.
Raise an exception.
Handle the exception.
An exception has four attributes:
Name provides a short description of the problem.
Type identifies the area of the error.
Exception Code gives a numeric representation of the exception.
Error message provides additional information about the exception.
The predefined divide-by-zero exception has the following values for the attributes:
Name = ZERO_DIVIDE
Type = ORA (from the Oracle engine)
Exception Code = C01476
Error message = divisor is equal to zero
The following is the typical syntax of an exception-handling PL/SQL block.
exception
when exception_1 THEN
statements
when exception_2 THEN
statements
...
exception_1 and exception_2 are the names of the predefined exceptions.
statements is the PL/SQL code that will be executed if the exception name is satisfied.