Oracle APEX Radio Group null option fix

APEX 5.1 introduced a template option that transformed radio groups into pill buttons.

I love this concept, it makes for a pleasant UI - an easier target for mouse clicks and finger taps.
I liked it so much I tried to do this myself prior to 5.1.

In 18.2 (fixed in 19.1), there's an issue with the way the null option presents for these radio groups - it's not in the (more...)

Customising APEX Validation Message

I'm an advocate for forum participation. This very post was a result of me learning something small just by watching the forums every morning.

In fact, quite a few of my posts spawn from forum activity, in part because future me can find my posts easier than forum discussions.

I wanted to share a collection of solutions for customising the notification message when a field is Required - turns out we have a few options.


AUSOUG Connect 2019

Australian Oracle User Group (AUSOUG) is holding their annual conference series in Perth & Melbourne this year, again this year, and I'm lucky enough to be at both events.

If you can, hold these days aside for Connect 2019, meet an interesting mix of people, and talk with them about your experiences. Seeing & hearing what other people are up to can be invaluable.

  • Monday 14th October – Rendezvous Hotel In Melbourne
  • Wednesday 16th October (more...)

MySQL Python Connector

While building my student image on Fedora 30, I installed the MySQL PHP Connector (php-mysqlndrp) but neglected to install the Python Connector. This adds the installation and basic test of the Python Connector to the original blog post.

You use the following command with a wildcard as a privileged user. The wildcard is necessary because you need to load two libraries to support Python 2.7 and 3.7, which are installed on Fedora 30. (more...)

How to install Oracle Database 18c XE on Windows

Get up and running with the free Oracle Database edition on Windows

PostgreSQL on Fedora 30

Installing PostreSQL 11 on Fedora 30 wasn’t straight forward but there were some instructions that helped. The first step requires you to update the yum repository, like this as the root user:

rpm -Uvh

Then, you install the PostgreSQL with this command as the root user:

dnf install postgresql11-server

After installing the PostreSQL Server I got a few errors with the symbolic links failing to resolve in the log files. (more...)

Making Longer Lists

For very long lists, we need the return values to be CLOBs. Alas, LISTAGG can only return VARCHAR2 lists, but XML and JSON aggregate functions can return CLOBs!

Misleading ORA- Message

Oracle error messages are more or less the best in the industry but time-to-time they saddle you with a bad or misleading message. For example, I was running one of the code modules from my Oracle Database 12c PL/SQL Programming book for a class exercise and got this error message:

ERROR at line 1:
ORA-22288: file or LOB operation  failed
ORA-06512: at "STUDENT.LOAD_CLOB_FROM_FILE", line 71
ORA-06512: at line 11

Oddly enough, it (more...)

MongoDB on Fedora 30

I found that MongoDB instructions changed significantly from a year ago. More or less, there was no pre-configured yum repository. Fortunately, the following web page was very helpful though not specific about Fedora.

Installing MongoDB 4.0 on Fedora 30 requires updating the yum repository. You need to create the mongodb.repo file as the root user in the /etc/yum.repos.d directory. The mongodb.repo file should contain the following:

name=MongoDB Repository
baseurl=https://repo. (more...)

Apache on Fedora 30

There was an option during the Fedora 30 Workstation installation to add the Apache Web Server, but you need to set it to start automatically. Unfortunately, there was no option to install PHP, which I thought odd because of how many web developers learn the trade first on PHP with a LAMP (Linux, Apache, MySQL, Perl/PHP/Python) stack. You see how to fix that shortcoming in this post and how to install and test PHP, mysqli (more...)

“No Primary Key item has been defined for form region”

Otherwise reported as “WWV_FLOW_FORM_REGION.NO_PRIMARY_KEY_ITEM” or merely “Internal error”, this bug caused me to waste hours of investigation, twice, because a simple Google search was not returning any results. This post is merely to remedy that situation.

On an APEX 19.1 page with a new Form region combined with an Interactive Grid region, when the user makes a change to a record and Submits the page, they get this error.

This is caused by (more...)

MySQL on Fedora 30

While updating my class image to Fedora 30, I noticed that it installed the Akonadi Server. The documentation on the Akonadi server lacked some straightforward documentation. It also offered a bundled set of software that limited how to approach MySQL development.

So, I removed all those packages with the following syntax:

dnf remove `rpm -qa | grep akonadi`

Löschung von automatisch erzeugten Indizes in Oracle 19c

Die automatische Generierung von Indizes durch das "Auto Indexing" in Oracle 19c sieht auf den ersten Blick wie ein ausgesprochen interessantes Feature aus. Das ist sie zweifellos auch. Wie gut sie funktioniert, ist ein anderes Thema. Franck Pachot zeigt, dass es zumindest nicht ganz leicht ist, die automatisch generierten Indizes wieder los zu werden: mit einem simplen "drop index" klappt das schon mal nicht - und ob manuelle Anpassungen in sys.ind$ tatsächlich eine gute (more...)

Menu Popup with Declarative List

In the past when I’ve needed to add half a dozen or more buttons to a page, I’ve sometimes encased them in a Collapsible region so that the user can slide them out of the way instead of clogging up the screen. Recently however I’ve started (sparingly) using a Menu Popup, as per this tutorial. The issue I have with this method, however, is that the menu items are defined in a shared component (more...)

Oracle Error Bash f(x)

My students always struggle initially with basic Linux skills. I wrote little function for their .bashrc file to help them avoid the frustration. It finds and displays all errors by file name, line number and error message for a collection of log files in a single directory (or folder).

  # Determine if any log files exist and check for errors.
  label="File Name:Line Number:Error Code"
  list=`ls ./*.$1 | wc -l`
  if [[ $list}  (more...)

Create Oracle User

After you create and provision the Oracle Database 11g XE, you create an instance with the following two step process.

  1. Create a student Oracle user account with the following command:

    CREATE USER student IDENTIFIED BY student

  2. Grant necessary privileges to the newly created student user:

    GRANT CREATE cluster, CREATE indextype, CREATE operator

How to install Oracle Linux on a Raspberry Pi – the easy way

In one of my past posts I showed how one can install Oracle Linux on a Raspberry Pi from a Mac via the command line. Luckily my colleague Philippe pointed out to me that things can be even much, much easier thanks to Etcher, an open source tool to flash SD cards and USB drives. … Continue reading "How to install Oracle Linux on a Raspberry Pi – the easy way"

Interval expressions

I just learned a lot about these critters thanks to an ODC forum question: how to calculate the difference between two dates in calendar years and months, days, hours, minutes and seconds.

Fedora 30 Missing Library

Having run into an obsolete library issue installing Oracle Database 18c XE on Fedora, Version 30, I opted to revert my student image to Oracle Database 11g XE. The installation went without issue but when I tried to log into SQL*Plus as the oracle user, I got the following error message:

sqlplus: error while loading shared libraries: cannot open shared object file: No such file or directory

The library (more...)

Fedora 30 Install Chrome

While building the new Fedora 30 Linux instance for my students, I needed to install the Google Chrome browser. Here are the instructions for installing the Chrome browser.

  1. As the root user, create the google-chrome.repo file in the /etc/yum.repos.d directory with the following information:


  2. Next, use the yum utility to install the Chrome browser:

    yum install -y google-chrome

    You should see (more...)