Handling PL/SQL Errors

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PL/SQL makes it easy to detect and process error conditions known as exceptions. When an error occurs, an exception is raised: normal processing stops, and control transfers to special exception-handling code, which comes at the end of any PL/SQL block. Each different exception is processed by a particular exception handler.

The exception handling for PL/SQL is different from the manual checking you might be used to from C programming, where you insert a check to make sure that every operation succeeded. Instead, the checks and calls to error routines are performed automatically, similar to the exception mechanism in Java programming.

Predefined exceptions are raised automatically for certain common error conditions involving variables or database operations. For example, if you try to divide a number by zero, PL/SQL raises the predefined exception ZERO_DIVIDE automatically. See "Summary of Predefined PL/SQL Exceptions".

You can declare exceptions of your own, for conditions that you decide are errors, or to correspond to database errors that normally result in ORA- error messages. When you detect a user-defined error condition, you execute a RAISE statement. See "Declaring PL/SQL Exceptions".

This section contains the following topics:

• Summary of Predefined PL/SQL Exceptions

• Using the Exception Handler

• Declaring PL/SQL Exceptions

• Scope Rules for PL/SQL Exceptions

• Continuing After an Exception Is Raised