Apex Training

In diesen "Krisenzeiten" erzählen alle darüber wie alles schlecht ist und was alles noch schlechter wird... Das ist ziemlich lässtig und es macht schlechte Laune. Aber, was ist denn eine Krise? In meinen Augen, das ist auch eine grosse Chance etwas zu ändern. Natürlich, zum Besseren. Und es gibt so viele Möglichkeiten. Zum Beispiel eigene Apex-Kenntnisse zu verbessern. Patrick, Dietmar und ich organisieren im März ein weiteres Training in Bensheim im Alee-Hotel Europa, um Best Practice Vorgehensweisen aus vielen erfolgreichen APEX Projekten zu lernen.

Neben der Informationen, die wir uns in zahlreichen APEX Projekten angeeignet haben, kommen die abendlichen Sessions (von 19:00-??:00) hinzu.

Dort stehen wir Ihnen für zusätzliche Hands-On Sessions zur Verfügung, um die Beispiele des Tages durchzuarbeiten oder auch, um konkrete Fragestellungen in Ihren aktuellen Projekten zu diskutieren.



Profitieren Sie von unserem jahrelangen und praxiserprobtem Oracle APEX Knowhow! Die Agenda und weitere Details findet Ihr auf der Web-Site wo Ihr Euch auch anmelden könnt.

Dynamic Charts

Whenever you need to create a chart with multiple series, you will go there and hardcode those series, creating an almost identical SQL for each one of them. As long as your values remain the same, that will be ok. But what if they change? Actualy, the solution is pretty simple - you need to create a PL/SQL Block to return all the series in one SQL. This example in my Demo Application shows how to write such a Function.



If you replace the column and table names, you can use the same function for all of your charts with multiple series.

Enjoy.

Tabular Form - Checkbox for Setting values to 'Y' or 'N'

This is also one of frequently asked question in the Apex Forum:

http://forums.oracle.com/forums/thread.jspa?threadID=493243

http://forums.oracle.com/forums/thread.jspa?threadID=714172

Using a checkbox for deleting rows is fine, but how do you use it if you want to flag the records and have a value updated depending on the checkbox status (valid/invalid, yes/no)?

It was Patrick Wolf who initially helped me to understand how a checkbox array works. He also created an example (on the fly) to show this can be managed. However, this example was based on a standard tabular form and it couldn't be reporoduced by many interested visitors of my Demo Application. Since this question has been repeated several times in the last couple of weeks, I decided to create a new example, which is based on a manual tabular form.



So, if you have a similar requirement, which is there in many cases, you may want to have a look here:

http://apex.oracle.com/pls/otn/f?p=31517:219

Validation with Ajax

As soon as you need to do some date or number validations using javascript, you will notice how cumbersome that attempt could be. Just recently, I had to programm an application which needed some date and number validations prior to the page submittion. I found that using ajax and letting your database do those kind of cheks is a quite elegant way.

In my Demo Application you will find an example

http://apex.oracle.com/pls/otn/f?p=31517:217

showing how easy it is to set it up.

Especially the date validation is funny. It will accept all kinds of date formats:

sep/15.08 03:16:00 AM

sep.15-08 03:16:00 AM

sep/15/08 03

and it will, of course, give you a user friendly message if you go too far and try entering something like this:

14.15-08 03:16:00 AM



or for

10.15-08 13:16:00 AM

you will receive



Try changing your browser language settings from english to any other language and do the excercise again.

OOW

It is time to get my luggage prepared for a long trip to San Francisco. This will be my first OOW. The trip will be long and exhausting but I am happy because I will get a chance to meet many of my colleagues, the most of which I know only through emails or the oracle forums.



I will arrive on Saturday afternoon and stay there till Thursday evening. These will be five exciting days and the programm is starting already on Sunday. I was invited by Dimitri Gielis to participate in the "Ask the Experts" session together with some well known names from the apex community: John Scott, David Peake, Scott Spendolini and Anton Nielsen.



Also, Dimitri announced an Apex Meetup on Tuesday evening.

The target is to catch as many apex sessions as possible. Unfortunatelly, some of them are starting at the same time. It will be hard to make a decission which one to take.

I will stay at the King George hotel, which is on a walk distance to the Moscone Center.

So, if you are also attending this great event and you are interested in apex, there is a good chance we will meet there.

Oracle Forums Splash

I got this message at least five times today:


at http://www.oracle.com/splash/forums/index.html.

Having to read this for the fifth time, I was just asking myself what sense do these couple of sentences make.

"Oracle forums is experiencing technical difficulty."

So, what kind of a technical difficulty are you experiencing day by day since almost a month? Furthermore: how long is this going to last? Another month? Or two? Any ideas?

"We are aware of the issue and are working as quick as possible to correct the issue."

Hm, are you sure you are?

"Please try again in a few moments."

Well, I did but it still doesn't work.

"We apologize for any inconvenience this may have caused."

Nice to know.

"To speak with an Oracle sales representative: 1.800.ORACLE1."

What should I tell him?

"To contact Oracle Corporate Headquarters from anywhere in the world: 1.650.506.7000."

I don't think they would want to talk to me.

"To get technical support in the United States: 1.800.633.0738."

Unfortunatelly, I belong to the rest of the world.

Guys, if this continues, I will never ever collect enogh points to become a guru.

What's wrong with the Oracle Forum?

As you probably noticed, the forums are either:

- not available at all or

- taking a lot of time to load or

- if they ever load, they are not working properly and showing errors if you try to create or update a posting.

If you manage to load those pages, you will notice that there are some new featueres implemented. Some of them are usefull. Like the new text editor (I realy like that one). Some of them are however questionable:

- the new reward system where you can get some points if you provide a helpfull or even a correct answer. The funniest thing is that the asker is supposed to say the answer someone provided is "correct".

- the fonts were changed to 11px which is not readable at all,

- the visited property they implemented are i.m.h.o. unneccessary because of the image showing if the posting was opened before or updated since. It is anoying too. Hard to read because of the grey color on a grey background.

I already asked the people who set it up if they are realy sure this makes sense. They didn't answer. Well, I am probably not the only one who asked.

Despite of the changes made, features I like or those I don't like, the most important thing though is the availability of the forum. And the fact is - it is not available since almost a week. Have they done a test before they upgraded? How did they test it? Did they ask the comunity about the changes? Maybe they should roll it back once again and consider a redisign using ApEx.

Oracle Text in Five Short Steps

Almost every application I create contains a BLOB (file) table for storing files available for a download. In the most of the cases it will store some documentation related to the application - user manuals, howto's and similar stuff. The download functionality is a nice thing but how about searching the content of those files? There are some examples arround showing how to do that in ApEx but in my opinion the most of them are far to complex. I created an example in my Demo Application, showing how to do that in less than five minutes:

http://apex.oracle.com/pls/otn/f?p=31517:76



This example includes the most frequently used functionalities:

1. mixed case search

2. highlighted snippets

3. index synchronization on commit

If you need more, you can always look into the Oracle Text Documentation.

Enjoy.

Form Validation and User Friendly Messages

I am getting this kind of questions quite often:

"I have report with form for modifications. After clicking on the link the form related to this report pops up. Often this is done by at least two users trying to modify one and the same record simultaneously. In such cases the application raises - "ORA-20001: Current version of data in database has changed since initiated update process. Error Unable to process row ....(table name)".

Could you give some advice or give and example how to handle this in a more user friendly manner?"

I created an example in my Demo Application showing how this can be done:

http://apex.oracle.com/pls/otn/f?p=31517:210

which also includes a step by step guideline.



There, you may test the validation by starting a concurrent update process and trying to update the data on the parent page.

Add Rows to a Standard Tabular Form using Item Value

There are many threads regarding this issue in the forum. Many of them without any answer. So, how do you add rows to your standard tabular form based on an item value?
If you follow this example:

http://apex.oracle.com/pls/otn/f?p=31517:209

you will see that you need three small adjustments to the standard process:

1. extend your SQL using UNION_ALL by adding a small SQL selecting NULL's from DUAL followed by CONNECT BY LEVEL <= :P1_ADD_ROWS_ITEM,

2. add a conditional branch, first in the sequence, passing a request ADD to your page

3. do a modification to the standard add rows process to add 0 rows

and there you go. You don't need to write a manual process to get that functionality
applied on your standard tabular form.



Enjoy.

Dynamic Tabular Form

It can happen that you get a requiremen similar to this one:

http://forums.oracle.com/forums/thread.jspa?threadID=691046

1. You have an unknow number of tables

2. You don't know the structure of the tables in advance

3. You still need forms for entering and maintaining data

The only solution that comes to my mind are dynamically created tabular forms. Tabular forms have already a bad reputation. Now, if you add the word "dynamical" to it, it will sound even more horrorful.

As I promised in the mentioned thread, I tried to create a working example. This is what I came up with:

http://apex.oracle.com/pls/otn/f?p=31517:195

It took me arround three hours to get that code together. Of course, this can be done much better - using a package and providing some additional functionalities like validations and other item types.

Multiple Cascading Select Lists (again)

This is an issue for many developers. I see a lot of questions and receive a lot of mails on this topic. I thought that demonstrating how to do that with two items would be enough to guess how to do it with more than that, since the approach is the same. However, there is nothing better than a step by step guide to get it working.

You will find the extended example here:

http://apex.oracle.com/pls/otn/f?p=31517:119



My advice, from what I have seen so far debuging the other people examples, is to:

1. be carefull with copy-paste and before you do it, think of replacing the given item , table and procedure names with your own,

2. test your on-demand processes in the SQL workshop first, to see if they run,

3. avoid multiplying your code through copy-paste. This makes it much easier to debug and

4. if you have no experience with a similar solution, try to reduce your scope and do it on a simple example first. Try using emp, dept tables like I do it in my Demo Application.

Enjoy.

Default Sorting of a Report

This was an interesting question:

"My requirement is Report should always display the original sequence (in the same way if I run the report in TOAD or SQL*PLUS, ...) and when I click the column heading then only it should do the actual sorting. Now, as soon as I set the sortable attribute to YES for a column and running the report for the first time... it's doing the sorting based on the that column."

So, how do you do that? Normaly, if you enable sorting on an apex report, it will save the sorting preference per user in an item and will call this preference next time you login.

I used the rownum to display the "original sequence" on initial load of the page and enabled the sorting on that column as well. Putting this column to be the first in the row on columns with enabled sorting and hiding it would do the trick. The second thing I did was to remove the sorting preference on the initial load and keep the rownum ordering as long as the user decides to sort the report.

You can view a working example here:

http://apex.oracle.com/pls/otn/f?p=31517:13

How to post your code in the Oracle Forum

This may have been already posted somewhere else. However, I still see people not knowing how to post their code properly. If you want to show your code in a posting on

http://forums.oracle.com

use the following tags and put your code between them

[code]

[/code]

This will show your code formated and readable like this

SELECT CASE
          WHEN cnt > 20
             THEN '<font color="red">' || cnt || '</font>'
          WHEN cnt <= 20
             THEN '<font color="green">' || cnt || '</font>'
       END AS x
  FROM "MYTABLE"
 WHERE TO_CHAR ("MYTABLE"."DATE", 'YYYY-MM-DD') >= '2007-04-01'
   AND "MYTABLE"."SERVCODE" <> 'OBS'

instead of something like this

SELECT CASE WHEN COUNT > 20 THEN '' || cnt || '' WHEN COUNT <= 20 THEN '' || cnt || '' END AS X from "MYTABLE" where TO_CHAR ("MYTABLE"."DATE",'YYYY-MM-DD') >='2007-04-01' and "MYTABLE"."SERVCODE" <>'OBS'

ApEx - Shopping Cart

There is a new example in my Demo Application showing how to create a simple shopping cart using Ajax and DHTML tipps from Carl Backstrom. This demo doesn't require a single submit and it shows how to utilize DHTML and Ajax to operate on collections. Since there is quite a bit of code and I am fairly busy at the moment, all the code is available only to those who have an admin login to my workspace.



You will find the example here:

http://apex.oracle.com/pls/otn/f?p=31517:159

Enjoy digging into it.

Over 500 named users of my Workspace

I started with the registration somewhere in January/February of this year. Up to now, more than 500 people applied for a login.


Within these five to six moths I answered arround 1200 emails regarding account and also many other questions related to ApEx. The number of emails I am getting per day is quite constant and I still haven't noticed a trend of those emails decreasing.

Sorting with ROWNUM

Creating a query and including the ROWNUM will work only for those reports, with disabled column sorting. Once you enable the column sorting, the ROWNUM will not show the right order. This is because ApEx does the sorting after determining the ROWNUM.

A simple trick can help you to overcome this issue. Just escape the ApEx internal #ROWNUM# like this:

SELECT '#ROWNUM#' SEQUENCE, empno, ename, sal
  FROM emp;

and it will give you the right ROWNUM regardless of your sorting.



You can see that working in this example in my Demo Application.

Pipelined Functions

The question in the forum was:

I need to allow my users to type in a list of names and return the names that are not in a table.

1. User types [ Tom Joe Bob MIKE ] into a Text Area item named :P2_NAME_CHECK

2. A table named CUST contains two rows with TOM and Bob in the 
   CUST_NAME column.

3. A report returns two rows JOE and MIKE. 

Usually, it is oposite. You want to show the list of users that match the criteria.

The solution for this problem is quite easy if you know how to use pipelined functions. This is a case where the pipelined functions shine. I created an example in my Demo Application showing how this can be done.



Basically, the pipelined function will create a row for all substrings returning no rows from the emp table, showing those substrings as rows.

Textfield Item - Submitting the Page

Normaly, if there are page items of type "Text Field" they will not submit the page unless you change them to "Text Field (always submits page when Enter pressed)". If you have only one item on you page of type "Text Field" this behaviour changes and the page will always submit if you press "Enter". Sometimes, you don't want this to happen. Especially, if you have some javascript attached to your field. To avoid that you can use the following trick:

1. create another item on you page of type "Text Field",

2. in the "HTML Form Element Attributes" of that item put

style="display:none"

The result is that the second item will not be displayed and the first item will not submit on pressing "Enter".

Two Tabular Forms on one Page

Recently there have been several discussions in the forum regarding multiple tabular forms on one page. I thought it is easy if you know how to create one tabular form manually, you will be able to do it for any other number of those forms. However, many participants of the forum do not share my opinion. This is why I decided to create a very basic example showing how that works. You will find it in my Demo Application together with the required code. If you want to see all the details, you may apply for an account following the instructions on the login page of my Demo Application.



Have fun.