Obsessed with Oracle PL/SQL

A few weeks ago, Mike Hichwa asked me to come up with a package that would implement a simple alerting utility: specify a triggering event (based on a query or a PL/SQL expression) and then take the specified actions when it is triggered. Seeing as he is my boss, I said "OK" and got to work (my favorite kind of work: writing some PL/SQL code). We did our usual bit to expand scope, then did our usual bit to agree that this is enough for a first pass. And then Mike said: "Go ahead and write a blog post about it, share it with the community." So here goes. The basic idea is we start up a job using DBMS_SCHEDULER that runs every N minutes. When it runs, it checks to see if any alerts need to be triggered. If so, it then takes one or more actions associated with that alert. Let's start with our tables. Utility configuration How often should the job wake up? Should it disable checking for alerts? What is the name of the "callout" for sending ema...

Another Oracle Dev Gym championship completed! Find below the rankings for the PL/SQL Challenge Championship for 2019. 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: MarkusId 2nd Place: mentzel.iudith 3rd Place: NielsHecker 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, we will make the championship as a whole available as a workout, so you can take it just like these players did. Finally, our deepest gratitude to our reviewer, Elic, who has once again performed an invaluable service to our community. Rank Name Total Time % Correct ...

Throughout 2019, over 1200 Oracle Database developers participated in the Oracle Dev Gym PL/SQL Challenge weekly tournament. The top 50 ranked players shown below will compete for top honors in a championship on February 18, 2020. The number in parentheses after their names are the number of championships in which they have already participated. As you can see, there are some very dedicated players here! Congratulations to all listed below on their accomplishment and best of luck in the upcoming competition! Name Rank Stelios Vlasopoulos (16) 1 mentzel.iudith (19) 2 NielsHecker (20) 3 Chad Lee (16) 4 Peterman (6) 5 siimkask (19) 6 _tiki_4_ (12) 7 Chase Mei (5) 8 Ludovic Szewczyk (4) 9 li_bao (7) 10 MarkusId (0) 11 Andrey Zaytsev (8) 12 Michal P. (3) 13 Arjun Barath (0) 14 Ivan Blanarik (13) ...

I published yet another PL/SQL puzzle on Twitter yesterday. Generated lots of interest and interesting replies. I don't think any single person caught everything , but as usual the community came through. I will repeat the puzzle here. If you haven't already seen it on Twitter, please try to solve it yourself before looking at my answer. What text can be removed from lines 3 though 12 in the code below so that after the anonymous block is executed, "121212" is still displayed on the screen? White space so you do not immediately see my answers.  :-) OK, let's dive in. Notice, first of all, that I asked about text  that can be removed, not lines. So you can remove entire lines or portions of lines. I refuse to accept that whitespace is text, so blank lines don't count. :-) Here are the opportunities for removal that I found: 4 - Remove the IN keyword. That's the default for parameters (though I generally always include it in my cod...

There are special member methods -  map  or  order  methods - that we use to tell Oracle Database how to compare two objects of the same datatype. This capability is critical when we want to perform an equality test in PL/SQL or when sorting objects in SQL. There is no default way to do this. In other words, if I create a simple object type, add it as a column to a table, and try to compare or sort, all I get are errors. Let's take a look. First I will create a table that has an object type as a column and add a couple of rows. CREATE TYPE food_ot AS OBJECT ( name VARCHAR2 (100), food_group VARCHAR2 (50), grown_in VARCHAR2 (100) ) NOT FINAL / CREATE TABLE meals ( served_on DATE, main_course food_ot ); / BEGIN INSERT INTO meals (served_on, main_course) VALUES (SYSDATE, food_ot ('Shrimp cocktail', 'PROTEIN', 'Ocean')); INSERT INTO meals (served_on, main_course) VALUES (SYSDATE + 1, food_ot ('House Salad...

My #ThanksOGB post: I've been working - and personally benefiting from - Oracle Database technology since 1987. I joined Oracle as a pre-sales consultant, which meant back then I was a techie sidekick for one or more Oracle salespeople. I moved on to various other roles and in 1992 left to become a consultant. Two years later, wrote a book on PL/SQL and have been obsessed with that language ever since. In 1999, I released the first version of utPLSQL - unit test for PLSQL, my version of JUnit. Worked for Quest for many years (bringing Quest Code Tester for Oracle to the market, among other things), and in 2014 rejoined Oracle, where I now lead a team of developer advocates (Blaine Carter, Chris Saxon, Connor McDonald, Dan McGhan). It's been a great life - and I expect it to keep on being such for a while to come. Part of the point of my little historical review, though, is that I was always paid to provide resources to the community (some of them free, like utPLSQL and m...

So far in my series on object-oriented development in Oracle Database, all manipulation of object type instances have taken place in PL/SQL. But as you may have guessed from the fact that you "CREATE OR REPLACE" object types, those types are also available for us in SQL. You can create relational tables of object types, called object tables. You can also define columns of relational tables whose datatypes are object types. In this post, I will explore both of these approaches. All the code you see below may be found in this  LiveSQL script , so you can get to know these features by playing around with them yourself. Object Tables It's easy to create object tables and work with the instances in those tables (both selecting and changing rows of data). Here's a simple example: CREATE TYPE food_ot AS OBJECT ( name VARCHAR2 (100), food_group VARCHAR2 (50), grown_in VARCHAR2 (100) ) NOT FINAL / CREATE TABLE food_table OF food_ot (CONSTRAINT food_ta...

On September 16, Larry Ellison announced a new Always Free tier for Oracle Cloud, which (for me) most importantly includes an Always Free Autonomous Oracle Database. For nothing but the "cost" of providing your credit card information (which is only used for identification purposes and is henceforth ignored until you decide to upgrade to a paid service), everyone in the world now can use the most powerful, most advanced database in the world FOR FREE. Of course, there are limits. But oh my what generous limits they are! Get lots more details here . And it's not just the amazing Autonomous Database (in both transaction processing and data warehouse flavors). You get Oracle Application Express (APEX) so you can build websites  writing very little code, and taking full advantage of your SQL and PL/SQL skills. You get SQL Developer to write what code you need and manage your database. You get Oracle Rest Data Services to build REST endpoints against your...

Find below the list of my blog posts in a series on working with object types (a.k.a, classes) in Oracle Database and, specifically, PL/SQL. This series is not intended to offer an in-depth training on object-oriented development; instead, it introduces basic O-O concepts and shows how they are implemented in Oracle Database with PL/SQL. Introduction to Object Types, Part 1 Object Types and Inheritance, Part 2 Object Types Methods, Part 3 Using Object Types in Relational Tables, Part 4 Comparison Methods for Object Types, Part 5 Dynamic Polymorphism - Why, What, How, Part 6 Each post also contains a link to a LiveSQL script, so you can try out all the code yourself.

Packages have subprograms (procedures and functions). Object types have methods. Object type methods are, still, procedures and functions. But there are also different types and characteristics of methods that only make sense in an object type, which supports inheritance and dynamic polymorphism. In this post, 3rd in my series on object types, I explore Static methods  Member methods  Non-instantiable methods  Invoking methods of super types All the code you see below can be run in Oracle LiveSQL through this script . Member Methods Member methods are methods applied to an instance of the type. Almost all the methods you ever write for an object type will be a member method. Assuming you are already familiar with writing PL/SQL functions and procedures, the most important thing to come up to speed on is the SELF value. Member methods have a built-in (implicit) parameter named SELF that denotes the object instance currently invoking the method. We'll...