Errors are especially likely during arithmetic calculations, string manipulation, and database operations. Example 11-19 is like Example 11-17 except that an enclosing block handles the exception that the exception handler in the inner block raises. When an exception is reraised, the first block searched is the enclosing block, not the current block. select dbms_warning.get_warning_setting_string() from dual; -- When we recompile the procedure, we will see a warning about the dead code.
The keyword OTHERS cannot appear in the list of exception names; it must appear by itself. You can define exceptions of your own in the declarative part of any PL/SQL block, subprogram, or package. Redeclared Predefined Exceptions Oracle recommends against redeclaring predefined exceptions—that is, declaring a user-defined exception name that is a predefined exception name. (For a list of predefined exception names, see Table 11-3.) Updates in the trigger wait for existing data locks to be released before proceeding.
In procedural statements, VALUE_ERROR is raised if the conversion of a character string into a number fails. (In SQL statements, INVALID_NUMBER is raised.) ZERO_DIVIDE A program attempts to divide Redeclaring Predefined Exceptions Remember, PL/SQL declares predefined exceptions globally in package STANDARD, so you need not declare them yourself. A crossedition trigger is a simple or compound DML trigger for use only in edition-based redefinition. Raise_application_error In PL/SQL, the pragma EXCEPTION_INIT tells the compiler to associate an exception name with an Oracle error number.
The subprogram is stored in the local database in compiled form, with a validated statement for accessing the remote database. Example 9-7 creates the view oe.order_info to display information about customers and their orders. Remember, no matter how severe the error is, you want to leave the database in a consistent state and avoid storing any bad data. https://docs.oracle.com/cd/B13789_01/appdev.101/b10807/07_errs.htm The variables and subprograms exist for the duration of the triggering statement.
With some better error checking, we could have avoided the exception entirely, by substituting a null for the answer if the denominator was zero: DECLARE stock_price NUMBER := 9.73; net_earnings NUMBER Pragma Exception_init Note: To run Example 9-9, you must have the EXECUTE privilege on the package DBMS_LOCK. So, your program cannot open that cursor inside the loop. Read more about internally defined exceptions in the documentation share|improve this answer answered Sep 8 '13 at 10:04 Ben 33k216499 What does this line do? - PRAGMA EXCEPTION_INIT( user_xcep,
Passing a zero to SQLERRM always returns the message normal, successful completion. Exceptions also improve reliability. Pl Sql Exception Handling Examples With this technique, you should use a FOR or WHILE loop to limit the number of attempts. Oracle Exception When Others However, when an exception is raised inside a cursor FOR loop, the cursor is closed implicitly before the handler is invoked.
Example 9-3 creates a conditional trigger that prints salary change information whenever a DELETE, INSERT, or UPDATE statement affects the EMPLOYEES table—unless that information is about the President. Example 11-23 Exception Handler Runs and Execution Ends DROP TABLE employees_temp; CREATE TABLE employees_temp AS SELECT employee_id, salary, commission_pct FROM employees; DECLARE sal_calc NUMBER(8,2); BEGIN INSERT INTO employees_temp (employee_id, salary, commission_pct) For example, in the Oracle Precompilers environment, any database changes made by a failed SQL statement or PL/SQL block are rolled back. To create a trigger that fires in response to a MERGE statement, create triggers on the INSERT and UPDATE statements to which the MERGE operation decomposes.
The invoker does not handle the exception, so PL/SQL returns an unhandled exception error to the host environment. Ora-06512 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 You code the pragma EXCEPTION_INIT in the declarative part of a PL/SQL block, subprogram, or package using the syntax PRAGMA EXCEPTION_INIT(exception_name, -Oracle_error_number); where exception_name is the name of a previously declared
The following block redeclares the predefined exception INVALID_NUMBER. Therefore, beyond its scope, a user-defined exception can be handled only with an OTHERS exception handler. Propagation of Exceptions Raised in Exception Handlers An exception raised in an exception handler propagates immediately to the enclosing block (or to the invoker or host environment if there is no END; The enclosing block does not handle the raised exception because the declaration of past_due in the sub-block prevails.
Consider the example below. If you exit a subprogram successfully, PL/SQL assigns values to OUT parameters. Put the sub-block inside a LOOP statement. You can define a complex view over the tables Book_table and Library_table to create a logical view of the library with sections and a collection of books in each section: CREATE
The exception handler cannot transfer control back to its own block. For details, see "Raising Exceptions Explicitly". For an example, see "Remote Exception Handling". If the company has zero earnings, the predefined exception ZERO_DIVIDE is raised.
Example 11-15 Exception Raised in Declaration is Not Handled DECLARE credit_limit CONSTANT NUMBER(3) := 5000; -- Maximum value is 999 BEGIN NULL; EXCEPTION WHEN VALUE_ERROR THEN DBMS_OUTPUT.PUT_LINE('Exception raised in declaration.'); END; Handling Exceptions Raised in Handlers When an exception occurs within an exception handler, that same handler cannot catch the exception. Query: SELECT salary FROM employees WHERE job_id = 'AD_PRES'; Result: SALARY ---------- 25200 1 row selected. Can I use my client's GPL software?
You can avoid unhandled exceptions by coding an OTHERS handler at the topmost level of every PL/SQL program. Except in an INSTEAD OF trigger, a triggering UPDATE statement can include a column list. Example 11-8 shows this. What is the WHEN OTHERS clause in Oracle?
When the i_is_one exception handler raises ZERO_DIVIDE, the exception propagates immediately to the invoker (therefore, the ZERO_DIVIDE exception handler does not handle it). Summary of Predefined PL/SQL Exceptions An internal exception is raised automatically if your PL/SQL program violates an Oracle rule or exceeds a system-dependent limit. A compound DML trigger has a greater performance benefit when it uses bulk SQL, described in "Bulk SQL and Bulk Binding". SYS_INVALID_ROWID The conversion of a character string into a universal rowid fails because the character string does not represent a valid rowid. TIMEOUT_ON_RESOURCE A time-out occurs while Oracle is
To find the number of X completed, when can I subtract two numbers and when do I have to count? Using Compound DML Triggers with Bulk Insertion A compound DML trigger is useful for accumulating rows destined for a second table so that you can periodically bulk-insert them. For more information, see "Handling FORALL Exceptions Immediately" and "Handling FORALL Exceptions After FORALL Statement Completes". Not the answer you're looking for?
For example, the following declaration raises an exception because the constant credit_limit cannot store numbers larger than 999: DECLARE credit_limit CONSTANT NUMBER(3) := 5000; -- raises an exception BEGIN ...