Pl/sql Trigger Error Handling
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occurs. Note: The database can detect only system-defined events. You cannot define your own events. Topics Overview of Triggers Reasons to Use Triggers DML Triggers System oracle trigger example Triggers Subprograms Invoked by Triggers Trigger Compilation, Invalidation, and Recompilation Exception Handling in oracle trigger tutorial Triggers Trigger Design Guidelines Trigger Restrictions Order in Which Triggers Fire Trigger Enabling and Disabling Trigger Changing and Debugging types of triggers in oracle Triggers and Oracle Database Data Transfer Utilities Triggers for Publishing Events Views for Information About Triggers Overview of Triggers Like a stored procedure, a trigger is a named PL/SQL unit that is triggers in oracle 11g stored in the database and can be invoked repeatedly. Unlike a stored procedure, you can enable and disable a trigger, but you cannot explicitly invoke it. While a trigger is enabled, the database automatically invokes it—that is, the trigger fires—whenever its triggering event occurs. While a trigger is disabled, it does not fire. You create a trigger with the CREATE TRIGGER statement. You specify the
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triggering event in terms of triggering statements and the item on which they act. The trigger is said to be created on or defined on the item, which is either a table, a view, a schema, or the database. You also specify the timing point, which determines whether the trigger fires before or after the triggering statement runs and whether it fires for each row that the triggering statement affects. By default, a trigger is created in the enabled state. For more information about the CREATE TRIGGER statement, see "CREATE TRIGGER Statement". If the trigger is created on a table or view, then the triggering event is composed of DML statements, and the trigger is called a DML trigger. For more information, see "DML Triggers". If the trigger is created on a schema or the database, then the triggering event is composed of either DDL or database operation statements, and the trigger is called a system trigger. For more information, see "System Triggers". A conditional trigger has a WHEN clause that specifies a SQL condition that the database evaluates for each row that the triggering statement affects. For more information about the WHE
Churchill Run-time errors arise from design faults, coding mistakes, hardware failures, and many other sources. Although you cannot anticipate all possible errors, you
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can plan to handle certain kinds of errors meaningful to your PL/SQL instead of trigger in oracle program. With many programming languages, unless you disable error checking, a run-time error such as stack overflow or what is trigger in oracle division by zero stops normal processing and returns control to the operating system. With PL/SQL, a mechanism called exception handling lets you "bulletproof" your program so that it can continue https://docs.oracle.com/cloud/latest/db112/LNPLS/triggers.htm operating in the presence of errors. 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 Propagate Reraising a PL/SQL Exception Handling Raised PL/SQL Exceptions Tips for Handling PL/SQL Errors Overview of PL/SQL Error Handling In PL/SQL, a warning https://docs.oracle.com/cd/A97630_01/appdev.920/a96624/07_errs.htm or error condition is called an exception. Exceptions can be internally defined (by the run-time system) or user defined. Examples of internally defined exceptions include division by zero and out of memory. Some common internal exceptions have predefined names, such as ZERO_DIVIDE and STORAGE_ERROR. The other internal exceptions can be given names. You can define exceptions of your own in the declarative part of any PL/SQL block, subprogram, or package. For example, you might define an exception named insufficient_funds to flag overdrawn bank accounts. Unlike internal exceptions, user-defined exceptions must be given names. When an error occurs, an exception is raised. That is, normal execution stops and control transfers to the exception-handling part of your PL/SQL block or subprogram. 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. To handle raised exceptions, you write separate routines called exception handlers. After an exception handler runs, the current block stops executing and the enclosing block resumes with the next statement. If there is no
here for a quick overview of the site Help Center Detailed answers to any questions http://stackoverflow.com/questions/15548176/pl-sql-oracle-error-handling you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers http://psoug.org/reference/exception_handling.html or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community in oracle of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up PL/SQL Oracle Error Handling up vote 1 down vote favorite 1 I've created a trigger that only allows a user to have 10 current placed orders. So now when the customer tries to placed triggers in oracle order number 11 the oracle database throws back a error. Well 3 errors. ORA-20000: You currently have 10 or more orders processing. ORA-06512: at "C3283535.TRG_ORDER_LIMIT", line 12 ORA-04088: error during execution of trigger 'C3283535.TRG_ORDER_LIMIT' The top error is one I've created using: raise_application_error(-20000, 'You currently have 10 or more orders processing.'); I just wondered after search and trying many ways how to change the error messages for the other two errors or even not show them all together to the user? Here is the code I've used create or replace trigger trg_order_limit before insert on placed_order for each row declare v_count number; begin -- Get current order count select count(order_id) into v_count from placed_order where fk1_customer_id = :new.fk1_customer_id; -- Raise exception if there are too many if v_count >= 10 then EXCEPTION WHEN OTHERS THEN raise_application_error(-20000, 'You currently have 10 or more orders processing.'); end if; end; Thanks a lot Richard oracle error-handling plsql share|improve this question edited Mar
Functions PSOUG Forum Oracle Blogs Search the Reference Library pages: FreeOracle MagazineSubscriptionsand Oracle White Papers Oracle Exception Handling Version 11.1 General NOTE: How Oracle Does Implicit Rollbacks Before executing an INSERT, UPDATE, or DELETE statement, Oracle marks an implicit savepoint (unavailable to you). If the statement fails, Oracle rolls back to the savepoint. Normally, just the failed SQL statement is rolled back, not the whole transaction. However, if the statement raises an unhandled exception, the host environment determines what is rolled back. If you exit a stored subprogram with an unhandled exception, PL/SQL does not assign values to OUT parameters. Also, PL/SQL does not roll back database work done by the subprogram. At the level of the SQL*Plus prompt, every update/insert/delete has one implicit savepoint, and also the invocation of any unnamed block. Below that, the unnamed block itself has 'sub' savepoints - one foreach insert/update/delete statement in it, and one for each subprogram unit. And so on down the line. If an error occurs, and that error is handled at any level by the time we're back at the SQL*Plus prompt, we only rollback to the immediate savepoint at the start of the update/insert/delete that errors. Otherwise we rollback to the top-level 'virtual' savepoint currently in existence, which is my offending unnamed block. That is, a handled error is handled and so can be dealt with without rolling back all the way to the top. It is handled and the transaction proceeds. Commits define the end of a transaction (and start of a new one) - rollbacks only define the end of a transaction if they rollback to the last commit, rather than savepoint (whether explicit or implicit). I came to my 'version' from the following by no means exhaustive tests: CASE 1: I created a table a with one column, a1 number, and at the sqlplus prompt inserted a row with a1 = 1. I then ran that unnamed block I referred in an earlier post that, without an exception handler, does the following: INSERT INTO a VALUES (2); INSERT INTO a VALUES (3); INSERT INTO a VALUES ('a'); As expected I get an unhandled error on the last line. When I do a select for everythin