Time travel with fixed_date

My Dad is a bit of a clever-clogs at the moment.
When he confidently predicted that Chelsea would beat Barcelona in the Champions League back in April,
I put this down to an affinity with the Chelsea squad which, lets face it, is rather nearer to his age-group than those at most other big clubs.
Since then however, he’s been on a roll, culminating in his unerring prediction that Sweden would beat France in the Euros.
This almost cephalopodic accuracy ( remember Paul the Octopus) is about to be put to it’s sternest test.
According to Dad, England will beat Italy on Sunday.
Hopefully, this is just another example of his prescience rather than a case of being swept up in the mood of the moment. Roy Hodgson has gone from being “why on did they go for this old codger” to “I always knew he was the man for the job” in the space of six weeks.
English football fans, fickle? I don’t know where you get that idea.
All of which provides a fairly tenuous link to the subject at hand – testing date sensitive changes in Oracle. Continue reading

Leading Zeros…the bleeding edge of TO_CHAR format masks

We’ve been busy playing with our new house.
Deb has re-arranged the furniture about three times since we moved in.
Well, she’s actually just specified where she wants the furniture, it’s me who has actually moved it about.
In fairness, she is the one who brings all the taste, style and interior design skills to our relationship. I’m more of the Igor who just does the legwork at her bidding.
My protestations about the importance of Euro 2012 have been met with the response that it can’t be that important a football tournament because Wales aren’t playing in it.
One of the benefits of moving into a new place is that stuff just works. You hit a light switch and the light comes on.
It’s a bit like using TO_CHAR to convert a number in Oracle really. Look, I’ll show you…
Continue reading

Running a Windows Batch file from DBMS_SCHEDULER

In an ideal world ….

Luton would have won the play-off final
I would have won the lottery by now
…and Oracle databases would run on Linux.

Out in the real world however, there are times when Oracle running on a Windows server is just unavoidable.
That’ll be the Real World with real data and real security issues, mixed in with – possibly – the real need to initiate a batch script from inside the database.
What follows are details of how to do this in Oracle 10g R2 running on a Windows server. Continue reading

Council Tax and calling functions from SQL in 11g

There is a frisson of excitement in our household at the moment. It’s not simply because the mighty Hammers on their way to Wembley. Oh no. It’s not even that Luton will be making the same journey with the same aim (i.e. promotion).
In fact, it has little or nothing to do with the end-of-season fun and games in the football world. The truth is, that we are finally moving from sunny Milton Keynes to …er… somewhere else in sunny Milton Keynes.
To mark this momentous occasion, Deb has busied herself with organizing the packing, working out where all the furniture is going in our new house and eyeing a whole range of utensils that will go with our new kitchen.
For my part, I’ve written a PL/SQL routine to apportion Council Tax Liability.
It should be noted that Deb has now applied to change her name to “The Long Suffering Deb” by deed pole.
Apart from exploring the algorithm required to apportion Council Tax ( for those outside the UK, it’s a sort of local tax on all domestic properties), I’ll also have a look at how 11g now allows at least three different ways of calling a database function from SQL. Continue reading

Just because you’re Paranoid…

…it doesn’t mean they’re not all out to get you !
No, this isn’t sage advice for the new manager of the England Football Team ( although Mr Hodgson will surely come to appreciate it’s wisdom in the very near future), but rather something to be mindful of when writing database code.

In my experience, there can be a worrying complacency among database developers when it comes to Security.
It’s as if they feel that their code is invulnerable, protected by that firewall thingy and inaccessible to those unsavoury types who want to crack their system and uncover the goodies therein.

Sometimes, it gets to the point where I begin to wonder, is it just me who worries about this sort of thing ? Am I just being a bit too paranoid ? Continue reading

Implicit Cursors are from Venus, Explicit Cursors are from Mars

Domestic bliss. There’s nothing like it. There’s certainly nothing like it in our house, particularly when I indulge in one of my endearing little foibles that is guaranteed to get Deb pouting like Angelina Jolie suffering a nasty reaction to a wasp-sting.
Whether it’s leaving the toilet seat up, or hanging my clothes up on the nearest floor, there are some days where I just can’t seem to do anything right.
Having said that, I must confess that I myself, am not a model of toleration. My own personal pout trigger is a query that looks something like this :

SELECT NVL(COUNT(*), 0)
FROM some_table;

I’ve seen this quite a bit recently, usually in the form of an explicit cursor.
Once I’ve got the rant about this out of my system, I’ll then look at how you might make single-row sub-queries a bit more efficient without ending up knee-deep in implicit cursors.
I’ll also ponder what it actually is that we really know about cursors. Continue reading

V$SGA_TARGET_ADVICE – The Need for Speed

My brother Steve lives near Brands Hatch in Kent. This is quite appropriate really. He’s always been a bit of a thrill-seeker. After his motorbike accident a few years back, he seems to have decided to treat the wheelchair as merely a transfer from two wheels to four.

“I’ve got a new Nissan” he told me the other day. “It’ll probably go round Brands Hatch quite slowly”.

What’s this ? Has the daredevil spirit suddenly disappeared and been replaced by a Nissan Micra ?

Er…No.

Not a Nissan Micra

Steve’s latest mode of transport is a Nissan GT-R. It looks like it’s breaking the speed limit, even when it’s parked on the drive.
Steve assures me that hitting the throttle is not so much a means of increasing speed as a command to engage warp drive.

All of which speed-freakery brings me to the point of this post, namely sizing the SGA_TARGET so that your database will be just that bit faster. Continue reading

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

Speed Dating – NLS_DATE FORMAT in Oracle

When dealing with dates in a program, I’ll tend to err on the side of caution and explicitly do the conversion from a varchar to a date, specifying the format so there’s no chance of anything unexpected happening if the program should run in a session with a different NLS_DATE_FORMAT from that I’m using.
However, if for example, I need to do a one-off data fix, sometimes, I just can’t be bothered with all that typing.
Continue reading