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Writing code to support multiple versions of Oracle Database

3rd in a series on conditional compilation. See end of post for links to all posts in the series.

Do you write code that must run on more than one version of Oracle Database? This is almost always the case for suppliers of "off the shelf" applications. And when confronted with this reality, most developers choose between these two options:

Use only those features available in all versions ("lowest common denominator" or LCD programming).
or Maintain separate copies of the code for each supported version, so you can take advantage of new features in later versions of the database ("sure to create a mess" or SCAM programming).

And let's face it, both have some serious drawbacks.

The LCD approach ensures that your code will compile on all supported versions. But you will sacrifice the ability to take advantage of new features in the later versions. That can be a high price to pay.

The SCAM approach, well, "sure to create a mess" says it all. Wh…
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Nine Years at the Oracle Dev Gym

Waaaaay back in 2010, on April 8 to be specific, I started a website called the PL/SQL Challenge. It featured a daily PL/SQL quiz (yes, that's right - a new quiz every weekday!) and gave Oracle Database developers a way to both deepen and demonstrate their expertise. Players were ranked and competed for top honors in our annual championships.

Not quite as waaaaay back, in 2014, I rejoined Oracle Corporation after 22 years away (from the company, not from the technology). The PL/SQL Challenge came with me, and a year later we rebranded it as the Oracle Dev Gym.

Today, we offer quizzes on SQL, PL/SQL, database design, logic, Java and Application Express. We've added workouts and classes.

Yesterday we celebrated the ninth anniversary of the Dev Gym / PL/SQL Challenge. And my oh my but Oracle Database developers have been busy!


Here are some stats from those nine years: Almost 35,000 developers and DBAs have taken quizzes on the site, a total of 1.27M answers submitted.They spent a…

Viewing conditionally compiled code: what will be run?

2nd in a series on conditional compilation. See end of post for links to all posts in the series.

In the previous (first) post in my series on conditional compilation, I covered use cases and presented some simple examples.

In this post, I show you how you can confirm what code is actually going to be executed after compilation. Without conditional compilation, this is of course a silly exercise. The code that is executed is the same as the code you see in your editor.

But with conditional compilation, the code that is compiled and therefore runs could depend on any of the following:
The version of the database in which it is compiledThe values of user-defined conditional compilation flagsThe values of pre-defined (system) conditional compilation flags, like ##plsq1_optimize_level It can be a little bit nerve-wracking for a developer to not be entirely sure what is going to execute, so we provide the DBMS_PREPROCESSOR package, with its two subprograms: print_post_processed_source - disp…

One exception handler for all packaged subprograms?

This question was submitted as a comment in one of my videos today:
Do we have to include an exception section for each individual subprogram or can we have a single handler for all subprograms? The quick answer is: if you want an exception raised in a procedure or function defined in a package, you need to add an exception to that subprogram.

I can certainly see why this question would come up. A package body can have its own exception handler. Here's an example:
CREATE OR REPLACE PACKAGE pkg AUTHID DEFINER IS PROCEDURE proc; END; / CREATE OR REPLACE PACKAGE BODY pkg IS PROCEDURE proc IS BEGIN RAISE NO_DATA_FOUND; END; BEGIN NULL; EXCEPTION WHEN NO_DATA_FOUND THEN DBMS_OUTPUT.put_line ('Was proc executed?'); END; / And it kinda, sorta looks like if I execute the following block, I will see "Was proc executed?" on my screen.
BEGIN pkg.proc; END; / But I would be wrong. Instead, I will see:
ORA-01403: no data found ORA-0651…

European Union Mandates All Business Logic in Database by 2020

DatelineDB: April 1st 2019

The European Union turned heads today with a surprise announcement:
Starting 1 January 2020, all business logic in applications must be made available via code stored inside the database. While we recommend that you use Oracle Database and PL/SQL, that will not be required. This position was apparently taken after close review of the groundbreaking research conducted by Toon Koppelaars of Oracle Corporation, in which he showed that by putting business logic in the database, the overall work - and therefore energy consumption - of the application is reduced, sometimes by as much as 235%. While improving the overall performance of the application by 500%.

A close confidant of the President of the European Union told DatelineDB that the EU would soon adopt a resolution stating that we are now in a climate emergency and every effort must be made in every aspect of human activity to slow down the warming of our planet.

"So the decision to require business lo…

An introduction to conditional compilation

1st in a series on conditional compilation. See end of post for links to all posts in the series.

Conditional compilation allows the compiler to compile selected parts of a program based on conditions you specify using $ syntax in PL/SQL. When you see statements like $IF, $ELSE, $END and $ERROR in your PL/SQL code, you are looking at conditional compilations, sometimes also referred to as "ifdef" processing.

There's a really good chance you've never taken advantage of conditional compilation in PL/SQL, so I thought I'd write up a few blog posts about why you might want to use it - and then how to put it to use.

Conditional compilation comes in very handy when you need to do any of the following:
Compile and run your PL/SQL code base on different versions of Oracle, taking advantage of features specific to those versions. Run certain code during testing and debugging, but then omit that code from the production code. Or vice versa. Install/compile different elements…

Results of the Oracle Dev Gym PL/SQL Challenge Championship for 2018

You will find below the rankings for the PL/SQL Challenge Championship for quizzes taken in 2018. The number next to the player's name is the number of times that player has participated in a championship. Below the table of results for this championship, you will find another list showing the championship history of each of these players.

Congratulations first and foremost to our top-ranked players:

1st Place: mentzel.iudith
2nd Place: Andrey Zaytsev
3rd Place: Tony Winn


Next, congratulations to everyone who played in the championship. We hope you found it entertaining, challenging and educational. And for those who were not able to participate in the championship, you can take the quizzes through the Practice feature. We will also make the championship as a whole available as a Test, so you can take it just like these players did.

Finally, many thanks and our deepest gratitude to our reviewers, especially Elic, who has once again performed an invaluable service to our community.

R…