Getting APEX to play with Ref Cursors

It’s that time of year again. Things are a bit tense around the house.
The other morning, I woke up to find that someone had placed a leek in my slippers.
Yes it’s Six Nations time again. England are playing Wales on Saturday. The lovely Debbie is getting into the spirit of the occasion…by exhibiting extreme antagonism to all things English.

Whilst the patriot in me would like to cheer on the Red Rose on Saturday, I have decided that discretion ( or in this case, cowardice) is the better part of valour and will instead, sit quietly in the corner, hoping for a draw. That way, I’ve not sold out completely and next week will be far more pleasant if Wales have not lost.

For those readers who know Rugby Union as merely another one of those odd games that we English let our former colonies win at, all you need to know is, the Welsh take this sport very seriously.

In the meantime, I’m trying to keep a low profile, which means playing around with APEX 4.1.

The heady excitement of discovering the first decent GUI development environment for PL/SQL programmers since Oracle Forms is now starting to be replaced by some of the harsh realities of modern web development.
For example, how can I reuse all those terribly useful functions that return Ref Cursors ?
I mean, they work fine in PHP and various other languages, and APEX itself is written in PL/SQL. Should be easy, shouldn’t it ?

Er, no.

APEX simply refuses to play. “I laugh in the face of your weakly typed Ref Cursor” it seems to say. Clearly, some persuasion is required if I’m not to end up with a lot of code locked away in my APEX application, unusable by any other programming language I might want to use to build a web front-end for my database.
The way to an APEX application’s heart is, as will become apparent, through Pipelined functions. Continue reading

Nested Tables – Flat-packed data in an Oracle Table

In the aftermath of the holiday season, there follows the inevitable January sales.
This year, I have been spared the inevitable trudge around the stores. Deb has hurt her knee and has therefore been restricted to browsing on-line.

I thought she “kneeded” cheering up, but to date, my attempts at lightening the mood, seem only to have given her the “kneedle”.

Sitting quietly, whilst Deb is wandering through various furniture store websites, I had cause to reflect on Oracle’s own version of Nested Tables.
These were introduced way back in Oracle 8, when Oracle confidently predicted that the Object-Relational Database was the way of the future.
Imagine if they were just bringing this feature out now. You can picture it. Larry would have spent months making disparaging remarks about IKEA’s occasional table range, before unveiling his own version, which was better, cheaper and more efficient.

Whilst you’re never going to be able to rest your pint on one, a Nested Table in Oracle may be useful on occasion. Continue reading

Help – DBMS_SCHEDULER keeps Spamming me…and can’t tell the time either

Sundays – a day of rest. Certainly true for me. Sunday morning is a time for lazing around leafing through the colour supplements and thinking about nothing in particular. Sunday 23rd October was a little bit different.
Wide-awake at 8 am ( I didn’t know that there was such a time as 8am on a Sunday), like several million others, I was wondering what would confront the All Blacks – the Gallic flair with which France had swept aside England or the Gallic shrug with which they had surrendered to Tonga ?
Look, I’m not really a New Zealander. Yes, I was born in Auckland but both my parents are English and I’ve lived most of my life in England. However, like anyone with a connection to the Land of the Long White Cloud, there is a part of my soul, however small, that takes the form of a Rugby ball.
At the end of the match, I was able to join my “fellow” Kiwis in, not so much paroxysms of joy as a huge collective sigh of relief.

On the whole though, I’d rather not have to see Sunday morning from that early on. So, if there is, for example, something that needs to run on my database on a Sunday morning, I’d rather the database just did it without my intervention.

What I plan to do here is :

  1. set up a scheduler job
  2. explore the ways in which we can control whether a class of job runs on a given database
  3. stop jobs running on database startup
  4. teach the scheduler how to tell the time – especially in terms of daylight saving

Continue reading

Oracle SQL and PL/SQL Coding Standards – Cat Herding for Dummies

Whilst in Montreal recently, Deb and I made a pilgrimage to the Circuit Giles Villeneuve, home of the Canadian Grand Prix. When not in use, the track is open to the public. It’s divided into two lanes – one for people to walk and cycle down down, and a one for people to drive down.
You can just imagine flying round in an F1 car. You come out of the excruciatingly slow L’epingle hairpin and build up to top speed as you tear down the Casino Straight. Ahead lies the final chicane before the start/finish line. A tricky right left combination with the treacherous curb on the inside of the last turn ready to spit the unwary into the Wall of Champions on the opposite side of the track.
At over 300 kph you start to think about spotting your braking point. Suddenly, this comes into view….

What do you think this is, a race track ?

… and now you know what it’s like to be a programmer, who has channeled raw inspiration through his or her dancing fingers to produce a thing of beauty and elegance…only to run into the QA person pointing out that the commas are in the wrong place according to page 823, paragraph 2 sub-section e of The Coding Standards.

Often measured in weight rather than the number of pages, Coding Standards documents are often outdated, arbitrary and just plain wrong.
On the other hand, their absence can cause much heartache, not least to those poor souls in support who are trying to maintain code where the Agilista philosophy of Code over Documentation has been taken to the ultimate extreme.

What follows is an attempt to make sense of the Coding Standards conundrum.
I’ll look at what I think a Coding Standards document should contain, and what it shouldn’t.
Then I’ll give some suggestions as to standards for Oracle SQL and PL/SQL which you can either embrace or throw rocks at, depending on your preference.
Before all of that however, I feel the need for some serious catharsis… Continue reading

Anchored Declarations and the Brownie Point Economy

This week’s hot conversational topic in the Nut and Squirrel was the Global Economic Crisis, with particular reference to a little-reported side-effect that has huge ramifications. I am, of course, referring to the devaluation of Brownie Points.

Unless you’re English, I guess some explanation may be called for at this point. So, at the risk of getting all anthropological…
Brownie Points are awarded by females to their mate for certain actions. When enough brownie points have been accrued, the male of the species can have these converted into a Pass.

The Pass can be used for a night out with the lads, at the footie, or whatever other pursuit is of interest.

This system is instinctively understood by females, although, due to the sudden and unexpected fluctuations in value, less so by the males.

You will often hear conversations such as :

“We’re going to Luton Saturday, their playing Mansfield, you reckon you can get a pass ?”
“Sorry, we’re at the Garden Centre on Saturday, need to earn some brownie points.”

This system goes under many different guises but is essentially the same the world over.
Lately however, it has become apparent that males are having to work harder for their brownie points than previously. The suspicion is that this is related to the retail price of women’s shoes.

What a mess. Where can you put your hard earned savings to ensure an index-linked return ?
Well, if you really want to know, you’ll have to read the Financial Times. Variables in PL/SQL, however, can be indexed-linked to database columns by the simple expedient of an anchored declaration. Continue reading

Oracle External Tables or What I did on my Holidays

This week’s missive is coming to you from the netbook. Deb and I have pushed the boat out this year and we’re currently in Canada for our holiday.
This has nothing at all to do with Oracle External Tables, but does explain the flavour of the examples that follow. Continue reading

DBMS_APPLICATION_INFO – Are we nearly there yet ?

Deb has come to the conclusion that, when on a long car journey, I’m not a great passenger.
“Are we nearly there yet ?” I enquire politely…usually around five minutes into a four-hour journey.
“No, not yet”, comes the patient reply.
“Are we almost nearly there yet ?”
“No, I’ll let you know when we are”, she responds with iron patience.
A few minutes pass…
“Are we almost nearly almost there ?”
At this point, I’m usually offered the option of walking the rest of the way.
It’s the same with long-running programs on the database. I want to know how far it’s gone and how far it’s got to go.
Oh, what Deb would do for an in-car equivalent of DBMS_APPLICATION_INFO.

Deb would probably have some sympathy with the DBA who gets a call from a user who has a process running and is, essentially, asking “are we nearly there yet ?”
Fortunately, with a bit of foresight and the judicious application of a little DBMS_APPLICATION_INFO magic, the answer to this question is right there in V$SESSION, or even V$SESSION_LONGOPS. Continue reading