Preprocessing External Tables

A question that comes up now and again is there a way in Oracle Database 11g Express Edition to mimic some behavior in the Oracle Standard or Enterprise editions. Many of these questions arise because developers want to migrate a behavior they’ve implemented in Java to the Express Edition. Sometimes the answer is no but many times the answer is yes. The yes answers come with a how.

This article answers the question: “How (more...)

External Tables

Oracle Database 9i introduced external tables. You can create external tables to load plain text files by using Oracle SQL*Loader. Alternatively, you can create external tables that load and unload files by using Oracle Data Pump. This article demonstrates both techniques.

You choose external tables that use Oracle SQL*Loader when you want to import plain text files. There are three types of plain text files. They are comma-separated value (CSV), tab-separated value (TSV), and position (more...)

MongoDB Update Statement

While discussing the pros and cons of MongoDB, my students wanted to know how to update a specific element in a collection. Collections are like tables in relational databases.

You create the users collection by inserting rows like this:

  { contact_account: "CA_20170321_0001"
  , first_name: "Jonathan"
  , middle_name: "Eoin"
  , last_name: "MacGregor"
  , addresses:
      street_address: ["1111 Broadway","Suite 101"]
    , city: "Oakland"
    , state: "CA"
    , zip: "94607" 
, {  (more...)

Linux mongod Service

The installation of MongoDB doesn’t do everything for you. In fact, the first time you start the mongod service, like this as the root user or sudoer user with the command:

service mongod start

A sudoer user will be prompted for their password, like

A typical MongoDB instance raises the following errors:

Redirecting to /bin/systemctl start mongod.service
[student@localhost cit425]$ mongo
MongoDB shell version v3.4.11
connecting to: mongodb://
MongoDB server  (more...)

Fedora 27 Screen Saver

Just back from Oracle OpenWorld and somebody desperately wants to know how to disable the 5 minute default screen saver setting in the KDE environment. OK, you navigate to the Fedora “f” in the lower left hand corner and choose System Settings, like:

In the System Setting menu page, select Desktop Behavior:

In the Desktop Behavior dialog, select Screen Locking. Change the default to something large like 360 for 6 hours.

As always, (more...)

Fedora SQL*Developer

After you download SQL Developer 18 on Fedora 27, you can install it with the yum utility, like

yum install -y sqldeveloper-

The installation should generate the following log file:

Last metadata expiration check: 2:26:23 ago on Sat 25 Aug 2018 07:10:16 PM MDT.
Dependencies resolved.
 Package               Arch            Version                      Repository             Size
 sqldeveloper          noarch            @commandline          338 M

Transaction Summary
Install  1  (more...)

APEX New Workspace

After you install APEX or upgrade a base APEX, you need to create workspaces. These instructions show you how to create a workspace in APEX 18. You have two options, you can use the base url while specifying the INTERNAL workspace.

  1. You start the process by accessing the Oracle APEX through the standard form by entering the following URL:


    • Workspace: INTERNAL
    • Username:  ADMIN
    • Password:  installation_system_password

  1. The better approach is to use the (more...)

APEX 4 to 18 Upgrade

While preparing my new instance for class, which uses Oracle 11g XE and Fedora 27, I got caught by the Oracle instructions. I should have got caught but when you’re in a hurry sometimes you don’t slow down enough to read it properly. Actually, for me it was the uppercase APEX_HOME that threw me for a moment. It looks too much like an environment variable. Step 5 of the upgrading instructions says:

  1. Log back into (more...)

MySQL 5.7.* and mysqli

After installing MySQL 5.7.22 and PHP 7.1.17 on Fedora 27, you need to install the mysqli library. You need to verify if the mysqli library is installed. You can do that with the following mysqli_check.php program:

Check mysqli Install
< ?php if (!function_exists('mysqli_init') && !extension_loaded('mysqli')) { print 'mysqli not installed.'; } else { print 'mysqli installed.'; } ?>

You test preceding PHP program with the following URL in a browser:


If the mysqli program isn’t installed, you can install it as follows by opening the yum interactive (more...)

Docker on Fedora 27

This walks you through the steps to install the Community Edition of Docker on Fedora 27. If you’ve been living under a rock for a few years, Docker is an open source container virtualization software.

Docker or Docker Community Edition is a necessary step if you want to install something like Microsoft’s SQL Server on Fedora because only these are supported platforms:

  • Red Hat Enterprise Linux 7.3 or 7.4
  • SUSE Linux Enterprise Server (more...)