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functions for error trapping in pl/sql Sunfield, Michigan

DUP_VAL_ON_INDEX ORA-00001 -1 Program attempted to insert duplicate values in a column that is constrained by a unique index. change due to INSERT, UPDATE, or DELETE statements). However, if you exit with an unhandled exception, PL/SQL does not assign values to OUT parameters (unless they are NOCOPY parameters). For information about autonomous routines, see "AUTONOMOUS_TRANSACTION Pragma".

IF number_on_hand < 1 THEN RAISE out_of_stock; END IF; EXCEPTION WHEN out_of_stock THEN -- handle the error END; You can also raise a predefined exception explicitly. If earnings are zero, the function DECODE returns a null. DECLARE ---------- sub-block begins past_due EXCEPTION; BEGIN ... The settings for the PLSQL_WARNINGS parameter are stored along with each compiled subprogram.

You might turn on all warnings during development, turn off all warnings when deploying for production, or turn on some warnings when working on a particular subprogram where you are concerned INVALID_CURSOR ORA-01001 -1001 There is an illegal cursor operation. This chapter discusses the following topics: Overview of PL/SQL Error Handling Advantages of PL/SQL Exceptions Predefined PL/SQL Exceptions Defining Your Own PL/SQL Exceptions How PL/SQL Exceptions Are Raised How PL/SQL Exceptions User-defined exceptions must be raised explicitly by RAISE statements, which can also raise predefined exceptions.

Example 4-1 Using the ZERO_DIVIDE predefined exception In this example, a PL/SQL program attempts to divide by 0. The optional OTHERS exception handler, which is always the last handler in a block or subprogram, acts as the handler for all exceptions not named specifically. PL/SQL Warning Categories PL/SQL warning messages are divided into categories, so that you can suppress or display groups of similar warnings during compilation. An application can call raise_application_error only from an executing stored subprogram (or method).

For lists of TimesTen-specific SQL and expressions, see "Compatibility Between TimesTen and Oracle Databases" in Oracle TimesTen Application-Tier Database Cache User's Guide. Syntax for Procedures The syntax for the WHEN OTHERS clause in a procedure is: CREATE [OR REPLACE] PROCEDURE procedure_name [ (parameter [,parameter]) ] IS [declaration_section] BEGIN executable_section EXCEPTION WHEN exception_name1 THEN Figure7-1, Figure7-2, and Figure7-3 illustrate the basic propagation rules. Consider the following example: BEGIN ...

Example 11-19 Exception Raised in Exception Handler is Handled by Enclosing Block CREATE PROCEDURE print_reciprocal (n NUMBER) AUTHID DEFINER IS BEGIN BEGIN DBMS_OUTPUT.PUT_LINE(1/n); EXCEPTION WHEN ZERO_DIVIDE THEN DBMS_OUTPUT.PUT_LINE('Error in inner block:'); SYS_INVALID_ROWID ORA-01410 The conversion of a character string into a universal rowid fails because the character string does not represent a valid rowid. PL/SQL procedure successfully completed. You can have any number of exception handlers, and each handler can associate a list of exceptions with a sequence of statements.

Redeclaring predefined exceptions is error prone because your local declaration overrides the global declaration. But, according to the scope rules, enclosing blocks cannot reference exceptions declared in a sub-block. CASE_NOT_FOUND ORA-06592 -6592 None of the choices in the WHEN clauses of a CASE statement were selected and there is no ELSE clause. Using Exception Handling we can test the code and avoid it from exiting abruptly.

DECLARE default_number NUMBER := 0; BEGIN INSERT INTO t VALUES(TO_NUMBER('100.00', '9G999')); EXCEPTION WHEN INVALID_NUMBER THEN DBMS_OUTPUT.PUT_LINE('Substituting default value for invalid number.'); INSERT INTO t VALUES(default_number); END; / Result: Substituting default value Finally, catch the exception and link the exception to a user-defined error number in RAISE_APPLICATION_ERROR. NOT_LOGGED_ON 01012 -1012 It is raised when a database call is issued without being connected to the database. Errors could also occur at other times, for example if a hardware failure with disk storage or memory causes a problem that has nothing to do with your code; but your

It could represent a mistake, or it could be intentionally hidden by a debug flag, so you might or might not want a warning message for it. With many programming languages, unless you disable error checking, a run-time error such as stack overflow or division by zero stops normal processing and returns control to the operating system. For example, if you declare an exception named invalid_number and then PL/SQL raises the predefined exception INVALID_NUMBER internally, a handler written for INVALID_NUMBER will not catch the internal exception. Error Code and Error Message Retrieval In an exception handler, for the exception being handled: You can retrieve the error code with the PL/SQL function SQLCODE, described in "SQLCODE Function".

If there is no handler for a user-defined exception, the calling application gets this error: ORA-06510: PL/SQL: unhandled user-defined exception Reraising a PL/SQL Exception Sometimes, you want to reraise an exception, EXCEPTION_INIT will associate a predefined Oracle error number to a programmer_defined exception name. So there seems to have been an invisible savepoint set just before the unnamed block ran. User-defined You can declare your own exceptions in the declarative part of any PL/SQL anonymous block, subprogram, or package.

SYS_INVALID_ROWID The conversion of a character string into a universal rowid fails because the character string does not represent a valid rowid. CASE 3: Then I reran everything, except the unnamed block had a generic when others then null; error trap, and the stored procedure had a generic when others the null; error For example, an exception-handling part could have this syntax: EXCEPTION WHEN ex_name_1 THEN statements_1 -- Exception handler WHEN ex_name_2 OR ex_name_3 THEN statements_2 -- Exception handler WHEN OTHERS THEN statements_3 -- Here you can list down as many as exceptions you want to handle.

RAISE statements can raise predefined exceptions, or user-defined exceptions whose names you decide. LOOP -- could be FOR i IN 1..10 LOOP to allow ten tries BEGIN -- sub-block begins SAVEPOINT start_transaction; -- mark a savepoint /* Remove rows from a table of survey You can also perform a sequence of DML operations where some might fail, and process the exceptions only after the entire operation is complete, as described in "Handling FORALL Exceptions with However, when an exception is raised inside a cursor FOR loop, the cursor is closed implicitly before the handler is invoked.

Outside an exception handler, you must specify the exception name. In the following example, you pass positive numbers and so get unwanted results: DECLARE err_msg VARCHAR2(100); BEGIN /* Get all Oracle error messages. */ FOR err_num IN 1..9999 LOOP err_msg := Internal exceptions are raised implicitly (automatically) by the run-time system. User-defined exceptions must be raised explicitly by RAISE statements, which can also raise predefined exceptions.

In PL/SQL, the pragma EXCEPTION_INIT tells the compiler to associate an exception name with an Oracle error number. SUBSCRIPT_OUTSIDE_LIMIT Your program references a nested table or varray element using an index number (-1 for example) that is outside the legal range. Databases SQL Oracle / PLSQL SQL Server MySQL MariaDB PostgreSQL SQLite MS Office Excel Access Word Web Development HTML CSS Color Picker Languages C Language More ASCII Table Linux UNIX Java If there is no enclosing block, control returns to the host environment.

Sometimes you can use error-checking code to avoid raising an exception, as in Example 11-7. An exception raised inside a handler propagates immediately to the enclosing block, which is searched to find a handler for this new exception. Example 11-1 shows several ALTER statements that set the value of PLSQL_WARNINGS. END; Normally, this is not a problem.

In Example 11-15, the VALUE_ERROR exception handler is in the same block as the declaration that raises VALUE_ERROR. Examples of internally defined exceptions include division by zero and out of memory. For internal exceptions, SQLCODE returns the number of the Oracle error. Non-predefined TimesTen error Any other standard TimesTen error These must be declared in the declarative section of your application.

Advantages of PL/SQL Exceptions Using exceptions for error handling has several advantages. dbms_output.put('Complete Call Stack:'); dbms_output.put(' Object Handle Line Number Object Name'); dbms_output.put_line(' ------------- ----------- -----------'); FOR v_CallRec in c_CallCur LOOP dbms_output.put(RPAD(' ' || v_CallRec.object_handle, 15)); dbms_output.put(RPAD(' Consider using a cursor. With PL/SQL, a mechanism called exception handling lets you "bulletproof" your program so that it can continue operating in the presence of errors.