Home > Pl Sql > Pl Sql Best Practices Error Handling

Pl Sql Best Practices Error Handling

Contents

If the condition (a Boolean expression) evaluates to TRUE, then the assertion program does nothing. Use Named Constants Oracle allocates 1,000 error numbers, between -20,000 and -20,999, for application-specific errors (such as "Employee must be 18 years old" or "Reservation date must be in the future"). You write applications that often assume the best of all possible worlds, hoping that your programs are bug-free, that users will enter only the correct data in only the correct fashion, Should this fact about exception handling change how you write your code? http://iipseconline.com/pl-sql/pl-sql-error-handling-best-practices.html

When writing functions, you may well decide that in the case of certain exceptions, you will want to return a value such as NULL, rather than allow an exception to propagate In the revised valerr procedure in Listing 2, the initialization section simply calls the initialize procedure. It is much better to strive for self-documenting code by hiding the implementation details, especially details involving the low-level "plumbing" of an application, such as exception handling and assertion logic. INVALID_NUMBER 01722 -1722 It is raised when the conversion of a character string into a number fails because the string does not represent a valid number.

Pl/sql Logging Best Practices

This is very poorly structured code: it's hard to understand and hard to maintain. Would there be no time in a universe with only light? He is also a senior technology advisor for Quest Software. Miscellaneous 5.

PKG-03: Freeze and build package specifications before implementing package bodies. PKG-04: Implement flexible, user-adjustable functionality using package state toggles and related techniques. Do I have to sacrifice this readability for improved error handling? Exception Handling In Oracle 11g Is this alternate history plausible? (Hard Sci-Fi, Realistic History) tr command has no effect when used in $() and saved in a variable Teaching a blind student MATLAB programming more hot

Set Guidelines before You Start Before you start writing any application code, you first need to decide on your overall strategy for error handling, as well as specific coding guidelines. Pl Sql Exception Handling Examples Use When Others for Unknown Exceptions Don't use WHEN OTHERS to grab any and every error. For example, it will warn us that some of the lines of code in our subprogram will never be run or are "unreachable" (PLW-6002). Why would breathing pure oxygen be a bad idea?

PKG-12: Use a standard format for packages that include comment headers for each type of element defined in the package. 9. Pl/sql Exception When Others It will be resulting quick. In such a situation, the PL/SQL runtime engine still registers the package as initialized and allows you to continue to reference subprograms and variables in the package. I pass in the following: an error number, the default SQLCODE , and an override error message.

Pl Sql Exception Handling Examples

Here are the guidelines I follow for these three exception types: Deliberate. https://www.safaribooksonline.com/library/view/oracle-plsql-best/0596001215/ch05.html Variables and Data Structures 3.1. Pl/sql Logging Best Practices There are a few edge cases, but those are very infrequent. Oracle Function Exception Return DECLARE c_id customers.id%type := &cc_id; c_name customers.name%type; c_addr customers.address%type; -- user defined exception ex_invalid_id EXCEPTION; BEGIN IF c_id <= 0 THEN RAISE ex_invalid_id; ELSE SELECT name, address INTO c_name, c_addr FROM

Program Construction 7.1. news Package Construction A.9. And oh, it is a recommended practice to turn on all compiler error checks. These two exceptions need different handling. Oracle Function Exception Return Null

Redesign your program so that you can avoid placing application logic in the exception section. Not the answer you're looking for? You can, however, hide these types of exceptions from your high-level application code in two ways. http://iipseconline.com/pl-sql/pl-sql-error-handling-example.html Movie about a board-game that asks the players touchy questions more hot questions question feed lang-sql about us tour help blog chat data legal privacy policy work here advertising info mobile

In which situations would it be best to handle the exception outside the procedure? –bruno Sep 9 '11 at 12:06 add a comment| up vote 3 down vote You should try Pl Sql Logging Example The existence of deliberate and unfortunate exceptions makes this impractical. Where is the kernel documentation?

Declaring Variables and Data Structures 3.2.

PKG-07: Insulate applications from Oracle version sensitivity using version-specific implementations. LOGIN_DENIED 01017 -1017 It is raised when s program attempts to log on to the database with an invalid username or password. PL/SQL behaves like this (or, to be more accurate, the Oracle PL/SQL development team decided to implement exception handling like this) because until local variables and constants are fully elaborated, you Oracle Pl Sql Best Practices Never call UTL_FILE.GET_LINE directly!

You might be tempted to simply pass back NULL to indicate "no data found," but that value (or, rather, lack of a value) may sometimes be a legitimate column value. As with the deliberate exception, the general rule is to avoid having to put application logic into the exception section. Previous Page Print PDF Next Page Advertisements Write for us FAQ's Helping Contact © Copyright 2016. check my blog Steven Feuerstein ([email protected]) is an authority on the PL/SQL language.

You can then feed this information to an error handler, to provide as much information as possible to the person debugging your code. We as a programmers need all the help the compilers can give to us ! A straightforward exercise might be to extend this package to write to a log file or pipe, instead of just using the standard DBMS_OUTPUT package. Oracle PL/SQL Best Practices SPECIAL OFFER: Upgrade this ebook with O’Reilly A Note Regarding Supplemental Files Dedication Preface Structure of This Book How to Use This Book Not All Best Practices

Here's what I suggest: If the default value for your variable or constant is a literal, assign the default on the same line with the declaration, but if the default value You say that it depends on "the actual funcionality implemented (..) within the procedures". An improved implementation would rely on dynamic SQL (either DBMS_SQL or native dynamic SQL) to automatically construct the program call and execute it. Because that is not the norm, this logic is often overlooked.

STYL-05: Name procedures with verb phrases and functions with noun phrases. PL/SQL provides exceptions, a flexible and powerful architecture that raises, traps, and handles errors. How are these errors and error messages defined? Program Construction A.8.

To understand this, consider this sequence of steps and PL/SQL statements: 1. This procedure displays or records the contents of any relevant variables or data structures—whatever you determine is of value inside that package. Using "traditional" PL/SQL logic, the above executable section would look something like this: BEGIN overdue.analyze_status ( title_in, start_date_in, report_info_out); overdue.send_report (report_info_out); EXCEPTION WHEN overdue.invalid_date THEN errpkg.report_and_go (msg_in => start_date_in); WHEN OTHERS END IF; /* Lots and lots of code ...

I think so. If none is provided, I use the default message stored in a messages table. Personally, I don't like all that distance. DEV-02: Ask for help after 30 minutes on a problem.