Getting a File Listing from a Directory in PL/SQL

It’s General Election time here in the UK.
Rather than the traditional two-way fight to form a government, this time around we seem to have a reasonably broad range of choice.
In addition to red and blue, we also have purple and – depending on where you live in the country, multiple shades of yellow and green.
The net effect is to leave the political landscape looking not so much like a rainbow as a nasty bruise.

The message coming across from the politicians is that everything that’s wrong in this country is down to foreigners – Eastern Europeans…or English (once again, depending on your location).
Strangely, the people who’ve been running our economy and public services for the last several years tend not to get much of a mention.
Whatever we end up choosing, our ancient electoral system is not set up to cater for so many parties attracting a significant share of support.

The resulting wrangling to cobble together a Coalition Government will be hampered somewhat by our – equally ancient – constitution.

That’s largely because, since Magna Carta, no-one’s bothered to write it down.

In olden times, if you wanted to find out what files were in a directory from inside the database, you’re options were pretty undocumented as well.
Fortunately, times have changed…

What I’m going to cover here is how to use an External Table pre-process to retrieve a file listing from a directory from inside the database.
Whilst this technique will work on any platform, I’m going to focus on Linux in the examples that follow…
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SQL*Plus Terminator Torture

“Leave that jar of Nutella alone, it’s got my name on it !”
The context in which Deb issued this injunction to me probably requires some explanation.
It was Friday evening.
Wales had just…well…come second in the latest installment of their eternal battle with the English through the medium of Rugby.
There was no alcohol left in the house.
And only one source of chocolate.
From the safety of the Cupboard under the stairs, to which I had retreated at kick-off – the Welsh do take their Rugby quite seriously – I wondered about my better half’s change of name.
Shorn of it’s chocolate hazelnut spread connotations, you might think that Nutella was quite an nice name for a girl.
It certainly seems appropriate if the “Girl” in question is slightly unhinged by a combination of wine and wounded national pride.

I was going to write something here about how Rugby players all look like the Terminator and use this as a way of introducting the topic at hand. However, I realise that this would simply be too contrived…even for me.
Instead, I’ll jump straight in…
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Installing and Configuring an Oracle Developer Day VirtualBox Image

It’s winter. I can tell. First, it’s still dark. Secondly it’s bitterly cold.
Standing on the platform at Milton Keynes Central, it would appear that we now have further evidence that being late is a train driver’s prerogative.
Hiking up the season ticket price is obviously the prerogative of train operators.
The last time I spent this much money to feel this cold, I found myself standing on the top of a mountain in the South Island of New Zealand.

Unlike the “Great” British Railway, installation and configuration of an Oracle Developer Day Appliance is somewhat simpler, not to mention more reliable.

What I’m going to cover here is the installation of a Developer Day Appliance in Virtual Box as well as some settings you might want to tweak to gain access to the Appliance Database from the Host OS.
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CREATE USER and ALTER USER – changing passwords and a New Year’s Resolution

Monday morning. The first day back at work in the New Year.
Still groggy, having been awoken from my slumber at the insistence of my Darth Vader Lego Alarm Clock, I stagger downstairs in search of coffee.
The clock was a Christmas present from Deb. Whilst clinking around the kitchen, I wonder whether it was intended as a subtle reminder of how she likes her coffee with only a little milk. Yes, she prefers it on the Dark Side.
Then I remember. I usually avoid New Year’s resolutions. I find them to be not unlike a cheap plastic toy at Christmas – there in the morning and then broken by the first afternoon.
This year however, is an exception.

In a recent post about APEX Authentication Schemes, I went to great lengths to ensure that a dynamic SQL statement to re-set a users password was safe from the possibility of injection.
Fortunately, Jeff Kemp took the time to point out a couple of issues with my approach.
As a result, this year, my resolution is to :
READ THE MANUAL.

What follows is the result of keeping this resolution ( so far, at least)…
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Implementing a Database Authentication Scheme in APEX

The following tangential opening was written especially for Scott Wesley in the hope that he’ll be minded to point out any errors in what follows. The same applies to Jeff Kemp ( although I don’t know if he’s into the AFL).
Unlike me, both of these guys are APEX experts.

Football. It’s a term that means different things to different people.
To a European, it’s most likely to be a reference to good old Association Football ( or Soccer).
To an American, it’s more likely to be the Grid-iron game.
A New Zealander will probably immediately think of Rugby Union.
An Australian ? Well, it’s probably a fair bet that they’ll think of Aussie Rules Football.

On the face of it, the rules appear rather arcane to an outsider. 18-a-side teams kicking, catching and punching something that resembles a Rugby ball around a pitch that resembles a cricket oval. Then there is the scoring system.
“Nice Behind”, to an AFL player is more likely to be taken as a compliment of their skill at the game than an appreciation of their anatomy.

Then again, it’s easy to scoff at any sport with which you are unfamiliar.
For example, Rugby could be characterised as 30 people chasing after an egg. Occasionally, they all stop and half of them go into some strange kind of group hug. I wonder if the backs ever get paranoid because they think the forwards are talking about them ?

As for soccer, even afficionados will acknowledge that there’s something a bit odd about a game where 22 millionares spend lots of time chasing after one ball…when they’re not rolling around in apparent agony after appearing to trip over an earth worm. I mean, the ball isn’t that expensive, surely they can afford one each ?

The point of all of this ? Well, what is considered to be obscure, eccentric, or just plain odd often depends on the perspective of the observer.

Take APEX authentication schemes for example.
Whilst not the default, Database Authentication is a scheme that is readily available. However, there doesn’t seem to be much written on this subject.

In contrast, there is a fair bit out there about APEX Custom Authentication. A lot of it would appear to re-enforce the idea that implementing security by hand is fraught with difficulty.
Just one example can be seen here.

If we were to approach this topic from the perspective of looking to migrate an elderly Oracle Forms application – where each user has their own database account – to APEX, we might be attracted to the idea of a Database Authentication Scheme and want to find out more.

What follows is my adventure through setting up such an Authentication Scheme.
Specifically, I’m going to cover :

  • Creating an APEX Database Authentication Scheme
  • Default behaviour
  • Adding a Verification Function to restrict access to a sub-set of Database Users
  • The vexed question of password resets

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