Wednesday, 1 October 2014

APEX 5 not so near

It seems I may have jumped the gun a little.
Idioms - the bane of ESL speakers?

Reading Anton's comment on a Friday afternoon got me a little too excited - upon reading it again Tuesday (we had a long weekend) I realised it was tongue in cheek.

So instead I went to Twitter to find what's being said at Oracle Open World about #orclapex. Turns out there will be a third early adopter - a feeling I got from something I read back in March.

There will also be a beta program for the first time - details to come since so far the only source of this information so far (for those not at OOW) is Twitter.

Who needs reporters anymore when you have real time feeds & photos from actual events? ;p

Friday, 26 September 2014

APEX 5 imminent?

It seems the release of APEX 5 is due within hours - just in time for OOW weekend.

To quote Anton here
Apex 5.0 is going to be released in a couple of hours
It's a long weekend here in Perth, and I have a footy grand final to watch - but no doubt I'll be installing it somewhere soon!

All that being said, apex.oracle.com is still on 4.2.5, so don't hold your breath for too long.

Stay tuned...

Monday, 22 September 2014

Leisure Suit Larry Ellison

Larry Ellison 1978
So at 70 years of age, the man who's been heading Oracle since before I was born is stepping down.

While I admit I'm far removed from the reality of the situation, I find it a little amusing how it's been deemed as a 'shake up' when a few paragraphs before he's quoted as saying this (referring to new co-CEOs)
“I am going to continue to do what I have been doing the past several years and they are going to continue doing what they have been doing the past several years,” 

So I bet he's probably going to be working in the same office, just the title under his name on the door will read "CTO". So for us at the coal face, surely this means he will spend more time directing the nature of the beast and leave operations to those who specialise. That sounds to me like a good thing.

I enjoyed this New York Times article, but writer Quentin Hardy made me read one of the last paragraphs a few times
Mr. Ellison does not leave his company entirely untroubled. Besides continuing challenges in cloud computing, including acquisitions and new competition, the company faces a raft of new types of databases, first developed inside Google and Yahoo, that also threaten the dominance of the relational database.

I've been thinking recently what the next generation of databases will be like. The relational model was revolutionary at the time, but bigger data and intelligent networking will surely one day reach another punctuated equilibrium. No doubt it will come from somewhere like contemporary giant Google.

If I was a passionate billionare I think I would have left the business behind long ago, along with the suit.
Circa 1993 - no eyebrows then either

Monday, 8 September 2014

Using Post-Authentication to run process after APEX login

A frequent requirement, and hence frequent question on the forums is
How do I run procedure x after the user has logged in?
This is often required for such tasks as determining user access, such as populating a restricted Application Item relating to a role like F_IS_ADMIN based on the username defined in substitition string APP_USER

Those new to APEX and unfamiliar with certain concepts may consider using an Application Computation, firing "On New Instance (new session)"
Application Computation Frequency

It sounds fair enough, and I remember doing the same thing when I was first learning APEX. The documentation on understanding page computations states
The computation point On New Instance executes the computation when a new session (or instance) is generated
This still isn't clear, but this actually fires when you first navigate to a page in your application - any page. This means when you first open a page like /apex/f?p=100:1, which may redirect you to the login page - the 'on new instance' event has already fired since APEX needed to provide you with a new session to render the home/login page.

In other words, these events can be generally described in the following order:
  • Open home page
    1. On New Instance (new session) - APP_USER is 'nobody'
    2. Redirect to login page
  • User enters username/password and submits
    1. Pre-Authentication 
    2. Validate credentials - APP_USER now set
    3. Post-Authentication
    4. Redirect to relevant page

I think I've only used 'On New Instance' once or twice, possibly to prime content of application items - but I use 'Post-Authentication' all the time to calculate values based on the user who just logged in.

Post-Authentication is defined in the Authentication Scheme, and expects the name of a stored procedure.
Shared Components -> Authentication Scheme
This stored procedure can be defined within the Authentication Scheme -> Source -> PL/SQL code as an anonymous block:
PROCEDURE post_authentication IS
BEGIN
  -- do stuff here

  null;
END 
post_authentication;

For better performance and code management you should place it within a PL/SQL package. That way it doesn't need to be interpreted dynamically every time a user logs in.

The Post-Authentication Procedure Name attribute just needs the name of the stored procedure, no semi-colon.
apx_auth_util.post_authentication

The PL/SQL may run something like:
IF v('APP_USER') = 'WESLEYS' THEN
  apex_util.set_session_state('F_IS_ADMIN','Y');
END IF;
I understand changes are coming in APEX 5 regarding when these events fire as you navigate between applications that share authentication.

This also reminds me of a little experiment I wrote ages ago to determine the order of page/application events.

Friday, 29 August 2014

Birds don't make the best ornithologists

This week I listened to episode 44 of one of my favourite podcasts - Inquiring Minds. It was an interview with David Epstein on the 'science of athletes'.

The podcast culminated with some really interesting points regarding the concept of 'talent' - what it really means, how it can be measured or influenced. One particularly interesting basis was the traditional idea that '10000 hours' training leads excellence in any particular skill, vs what's in the genes.
Exhibit A: Kalenjin (regional Kenya) long distance runners. Well worth the listen to get the full detail.

Another interesting example was a female softball player Jennie Finch that made the news in 2004 striking out professional male players. The men expected to have no problems hitting her out of the park, but players confused their perceived reliance on ability to track ball in flight and rely on 'talented' reaction time with what they actually do.

(Getty Images)
In fact, this article I found when searching for Jennie Finch goes into very similar detail (since it's written by the interviewee!) and suggests
Given the speed of the pitch and the limitations of our physiology, it seems to be a miracle that anybody hits the ball at all.
It's apparent that players interpret the pitcher's shoulder, body rotation, ball thread rotation in flight and other factors to calculate the region the hitter expects the ball to fly by. But since thrown underarm, all information players read to calculate where the ball will land - is lost.
They've even got a bigger, slower ball to hit.

They found likeness to chess, where a good player sees the entire board - a number of moves ahead.
I found likeness to pool/snooker. After the break I might see the next 4-5 balls I can pot in a row. Newer players are often overwhelmed just to work out which one to try.

I'm sure my game would slow right down if was faced with a different shaped table.
Pool tables I wouldn't enjoy
I don't do the topic justice, but I recommend both this particular episode and the podcast in general. I listen to podcast in my commute to work - I play to post my favourites one day, I'd be interested to hear any other recommendations.

The blog post title? A quote from David during the interview

Friday, 22 August 2014

OTech Magazine Issue 4 - APEX 5 and much more

Well it's the second half of August and this is my first real post for the month. There are two very good reasons for this:

1) We've just completed a major implementation at one of our clients - a tablet based application using APEX, which completely changes the face of a major arm of the business. It's a groundbreaking application with only one peer in the industry - which users are already claiming superiority to and it's had years to mature. It's been a very enjoyable project with a glowing success story - kudos to my Sage colleagues and the entire team.

2) Douwe Pieter van den Bos from OTech Magazine asked if I would like to contribute to their next quarterly issue, but with a catch - it had to be submitted pretty soon as they were already finalising the content. I hadn't actually heard of it until I received a LinkedIn request from Douwe. This is only the fourth issue so I don't feel too bad. I browsed through the previous issues and read what the magazine is all about and it was something to which I was more than happy to contribute.

I think Douwe had seen my series of blog posts on APEX 5 and asked if I would like to add something on that. I also recently presented on the topic in Perth, so I figured my Prezi was something I could quickly adopt into prose. It was a bit of a rush job and I feel it shows a little, but I plan to do the presentation again as an ODTUG webinar, so stay tuned if you want to hear the original format.

OTech Magazine #4
OTech Magazine is free, independently produced, well polished, digitally formatted for Oracle professionals. The editors carefully select authors & articles in efforts to obtain high quality content. My APEX 5 (EA2) article is in the just released "Summer 2014" issue. Yep, I quoted that because I'm not sure that global products should relate to a season - especially since I'm currently living in a "winter" climate. Yep, I quoted that too because we're enjoying mostly 22C sunny days - I blame climate change.

It confuses the heck out of me when I see a movie advertised for release in Winter 2015 - what range of months is that?!

Anyway, check out the OTech Magazine - you'll find yourself wanting to read the past issues.
http://www.otechmag.com/2014/otech-magazine-summer-2014/

Demystifying Oracle Unpivot

A couple of years ago I posted a simple example using PIVOT, converting rows to columns with the classic example of figures by months.

Oracle 11g R1 also introduced the UNPIVOT function, allowing columns to be converted into rows.

Problem

I've created an example that lists cities by row, but two attractions as two columns, with pairing attributes describing the reason for the attraction.
create table aus_attractions(id  number, city varchar2(50)
  , attraction1 varchar2(50)
  , attraction2 varchar2(50)
  , reason1 varchar2(50)
  , reason2 varchar2(50)
  );
insert into aus_attractions values (1, 'Perth','weather','beaches','sunny','white sand');
insert into aus_attractions values (2, 'Sydney','bridge','blue mountains','climb','scenic');
insert into aus_attractions values (3, 'Melbourne','culture','aussie rules','activities','crowds');

select id, city
      ,attraction1,attraction2
      ,reason1, reason2
from aus_attractions;

Not optimal relational data design

I'd like to see each attraction by row - 6 rows instead of 3.

You could solve this with a UNION ALL, and/or a WITH - but one day "they" will ask for 5 options, might as well unpivot.

Solution

Then we can turn our original statement into an inline view, serving the unpivot function.
select id, city, attraction, reason, rec_nbr
from ( -- original query:
     (select id, city
         ,attraction1,attraction2
         ,reason1, reason2
   from aus_attractions
   )
 unpivot               -- the magic operator
 ((attraction, reason) -- names of replacement columns
  for rec_nbr in (     -- new column defining data source in literal alias below
   -- split each group of fields in here
   (attraction1, reason1) as 'REC1' 
  ,(attraction2, reason2) as 'REC2'
  )
 )
);

ID      CITY       ATTRACTION        REASON       REC_NBR
------  ---------- ----------------- ------------ -------
1       Perth      weather           sunny        REC1
1       Perth      beaches           white sand   REC2
2       Sydney     bridge            climb        REC1
2       Sydney     blue mountains    scenic       REC2
3       Melbourne  culture           activities   REC1
3       Melbourne  aussie rules      crowds       REC2

6 rows selected
Awesome.
Unpivoted data

Simple, once you've done it the first time...

Documentation

Oracle SQL Language Reference
Oracle Data Warehousing Guide - SQL for Analysis and Reporting

Other great examples of varying depth

OTN - Arup Nanda
Oracle-Base - Tim Hall
Oracle FAQ - Unpivot
Oracle-developer.net - Adrian Billington
AMIS - Lucas Jellema
SQL Snippets: Columns to Rows - UNPIVOT (11g)

If you're not already using the above sites for good reference material, you're missing out.