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Pl Sql Error Checking
You can place RAISE statements for a given exception anywhere within the scope of that exception. THEN -- handle the error WHEN OTHERS THEN -- handle all other errors END; If you want two or more exceptions to execute the same sequence of statements, list the exception A stored PL/SQL unit Use an ALTER statement from "ALTER Statements" with its compiler_parameters_clause. All rights reserved.
Before starting the transaction, mark a savepoint. DECLARE Child_rec_exception EXCEPTION; PRAGMA EXCEPTION_INIT (Child_rec_exception, -2292); BEGIN Delete FROM product where product_id= 104; EXCEPTION WHEN Child_rec_exception THEN Dbms_output.put_line('Child records are present for this product_id.'); END; / c) User-defined Exceptions Apart 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 Declare a user-defined exception in the declaration section. 2. https://docs.oracle.com/cd/A97630_01/appdev.920/a96624/07_errs.htm
Pl Sql Exception Handling Best Practices
Catching Unhandled Exceptions Remember, if it cannot find a handler for a raised exception, PL/SQL returns an unhandled exception error to the host environment, which determines the outcome. WHEN OTHERS THEN -- optional handler sequence_of_statements3 END; To catch raised exceptions, you write exception handlers. If you neglect to code a check, the error goes undetected and is likely to cause other, seemingly unrelated errors.
To handle raised exceptions, you write separate routines called exception handlers. Pl Sql Exception When Others You declare an exception by introducing its name, followed by the keyword EXCEPTION. IF ... 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
In the sub-block, before the transaction starts, mark a savepoint. Exception No Data Found Oracle Example 11-5 gives the name deadlock_detected to the internally defined exception ORA-00060 (deadlock detected while waiting for resource) and uses the name in an exception handler. Exceptions declared in a block are considered local to that block and global to all its sub-blocks. Example 11-25 uses the preceding technique to retry a transaction whose INSERT statement raises the predefined exception DUP_VAL_ON_INDEX if the value of res_name is not unique.
Pl Sql Exception When Others
Example 11-25 Retrying Transaction After Handling Exception DROP TABLE results; CREATE TABLE results ( res_name VARCHAR(20), res_answer VARCHAR2(3) ); CREATE UNIQUE INDEX res_name_ix ON results (res_name); INSERT INTO results (res_name, res_answer) Continuing after an Exception Is Raised An exception handler lets you recover from an otherwise fatal error before exiting a block. Pl Sql Exception Handling Best Practices Errors are especially likely during arithmetic calculations, string manipulation, and database operations. Pl Sql Continue After Exception EXCEPTION WHEN NO_DATA_FOUND THEN -- catches all 'no data found' errors Exceptions improve readability by letting you isolate error-handling routines.
The pragma must appear somewhere after the exception declaration in the same declarative section, as shown in the following example: DECLARE deadlock_detected EXCEPTION; PRAGMA EXCEPTION_INIT(deadlock_detected, -60); BEGIN ... -- Some operation Because predefined exceptions have names, you can write exception handlers specifically for them. The settings for the PLSQL_WARNINGS parameter are stored along with each compiled subprogram. In the exception-handling part, you can include exception handlers for both specific and unknown errors. Exception Handling In Oracle Interview Questions
SELECT ... So, PL/SQL predefines some common Oracle errors as exceptions. The technique is: Encase the transaction in a sub-block. To have the enclosing block handle the raised exception, you must remove its declaration from the sub-block or define an OTHERS handler.
However, when an exception is raised inside a cursor FOR loop, the cursor is closed implicitly before the handler is invoked. Functions For Error Trapping Are Contained In Which Section Of A Pl/sql Block When you see an error stack, or sequence of error messages, the one on top is the one that you can trap and handle. Figure 7-1 Propagation Rules: Example 1 Text description of the illustration pls81009_propagation_rules_example1.gif Figure 7-2 Propagation Rules: Example 2 Text description of the illustration pls81010_propagation_rules_example2.gif Figure 7-3 Propagation Rules: Example 3 Text
To see warnings (and errors) generated during compilation, either query the static data dictionary view *_ERRORS (described in Oracle Database Reference) or, in the SQL*Plus environment, use the command SHOW ERRORS.
The message code of a PL/SQL warning has the form PLW-nnnnn. For example: EXCEPTION WHEN INVALID_NUMBER THEN INSERT INTO ... -- might raise DUP_VAL_ON_INDEX WHEN DUP_VAL_ON_INDEX THEN ... -- cannot catch the exception END; Branching to or from an Exception Handler A User-defined You can declare your own exceptions in the declarative part of any PL/SQL anonymous block, subprogram, or package. Oracle Cursor Exception Handling Within A Loop You can pass an error number to SQLERRM, in which case SQLERRM returns the message associated with that error number.
The above program displays the name and address of a customer whose ID is given. The other internal exceptions can be given names. EXCEPTION WHEN deadlock_detected THEN ... When an error occurs, an exception is raised.
If there are nested PL/SQL blocks like this. CALL DBMS_WARNING.SET_WARNING_SETTING_STRING('ENABLE:ALL' ,'SESSION'); -- Check the current warning setting. Example 11-10 Explicitly Raising Predefined Exception DROP TABLE t; CREATE TABLE t (c NUMBER); CREATE PROCEDURE p (n NUMBER) AUTHID DEFINER IS default_number NUMBER := 0; BEGIN IF n < 0 For example, in the Oracle Precompilers environment, any database changes made by a failed SQL statement or PL/SQL block are rolled back.
There are two ways to handle unnamed sysyem exceptions: 1. CASE_NOT_FOUND None of the choices in the WHEN clauses of a CASE statement is selected, and there is no ELSE clause. VALUE_ERROR 06502 -6502 It is raised when an arithmetic, conversion, truncation, or size-constraint error occurs. In Example 11-10, the procedure raises the predefined exception INVALID_NUMBER either explicitly or implicitly, and the INVALID_NUMBER exception handler always handles it.
CREATE OR REPLACE PROCEDURE dead_code AS x number := 10; BEGIN if x = 10 then x := 20; else x := 100; -- dead code (never reached) end if; END Unlike internal exceptions, user-defined exceptions must be given names. Figure 11-2 Exception Propagates from Inner Block to Outer Block Description of "Figure 11-2 Exception Propagates from Inner Block to Outer Block" In Figure 11-3, the inner block raises exception C.