Exception error Handling

Fifth. Exception error handling

1 Exception Handling

Exception handling is used to handle unexpected events during normal execution, the exception of the block handles predefined errors and custom errors, and The program automatically terminates the entire program as soon as the PL/SQL block generates an exception and does not indicate how it should be handled

There are three types of exception errors

1 pre-defined errors

Oracle 's pre-defined exception conditions are approximately Four, and the handling of this anomaly is no longer defined in the program, with Oracle

Automatically throws it

2 non-pre-defined errors

Other standard Oracle errors, the handling of this exception requires the user to define it in the program, which is then automatically raised by Oracle

3 user-defined error

During the execution of the program, it appears that the programmer considers the abnormal situation. For this exception handling scenario, the user is required to define it in the program and then explicitly throws it in the program

Structure of exception handling:

Exception

When First_exception then workaround 1

When Second_exception then workaround 2

When others then workaround 3

End;

4 Examples of non-pre-defined exceptions

Declare

E_daleteid_exception exception;

pragma exception_inti (e_daleteid_exception,-2292); this is equivalent to encapsulating the condition of an exception trigger.

BEGIN

DELETE from employess WHERE employ_id=100;

EXCEPTION

When E_daleteid_exception then exception handling Operation

5 user-defined error examples

Declare

E_too_high_sal exception;

V_sal employees.salary&type;

Begin

Select salary into V_sal from employees where employee_id=100;

If v_sal>10000

then raise E_too_high_sal;

End if;

Exception

When E_too_high_sal and then exception handling

End;

Exception error Handling