A short notice on installing Oracle 11g database.
I installed it on Oracle Linux 5 with an alias/SID bigger than 8 characters; in my case ora11g2se. This results in an error when starting the database: 

ORA-01078: failure in processing system parameters

LRM-00109: could not open parameter file '/home/oracle/app/oracle/product/11.2.0/dbhome_1/dbs/initora11g2se.ora'

The error message should state: could not open parameter file 'spfileora11g2se.ora', because thát is the file missing.
When you look in your $ORACLE_HOME/dbs directory you'll find a spfileora11g2s.ora. Just copy it with the full database alias:

cp spfileora11g2s.ora spfileora11g2se.ora

and start the engines... uh ... database!

If you want to install an Oracle 11g database in Oracle Linux 5 which is installed in a VM (Virtualbox); here are the steps I followed, with success.

I presume you installed the Virtualbox, Guest Additions, Oracle Linux 5 with success.

Start the Oracle Linux 5 VM

We first prepare the machine for installation of the Oracle11g database. This will automatically configure Oracle Linux for Oracle 11g.
In a terminal type the following:

cd /etc/yum.repos.d

wget http://public-yum.oracle.com/public-yum-el5.repo

Now, we start an editor and open the .repo file:

gedit public-yum-el5.repo

Adjust the lines with heading [el5_latest] and [ol5_UEK_latest].
Check and change enabled=0 to enabled=1.
Close and save.

Start the following as root (su):

yum install oracle-validated

Check if you have an oracle user and that it is member of the oinstall and dba group.

When all is done you can start installing the Oracle 11g database.
Make sure you can access the (unzipped) software in your Virtual Machine (VM).
I unzipped the Oracle software to a directory and created a shared directory and copied all the software while in the VM to a directory in the VM (e.g. /home/OraDB11g/).

 Now,  in a terminal go to the directory where you put the software and start the installation as the oracle user.

./runInstaller

 follow the installer instructions and your Oracle 11g database software is installed.

If you install in a 64 bit architecture, you can receive an error message about ODBC (i386) missing. You can ignore the warning.

If other problems occur, check the internet. There's a lot of information available.

 

 

Oracle Designer is not supported in Windows 7. But, you can install and use it. There is however (at least) one bug.

When Oracle Designer generates a Forms module it calculates the width of items based on the system font size. And there is where it all goes wrong... somehow it grabs somewhere a system value and - when upgrading from an older MS Windows version - all your screen items become smaller, possible resulting in not fully displaying the item's content.

In fact there's no problem when you start using Oracle Designer for the first time and you install it on Windows 7. But, do these people exist? ;)

KEEP DENSE_RANK is great functionality within the Oracle database; here is why.

Suppose you have a table with a date and a status field:

table mytable
( date_created date
, status varchar2 )

Status can have 2 values: A or B

If you want to fetch only 1 row based on the most recent date_created you would do something like this:

select *
from mytable
where date_created = (select max(date_created) from mytable);

No problem so far... 
But, suppose you want to have the row with the most recent date_created for status A, if it exists and if not, you just want to have the most recent date_created.
In the old times your solution would be something like this:

select *
from mytable
where date_created = (select max(date_created) from mytable where status = 'A')
or 
not exists ( select 1 from mytable where status = 'A' )
and date_created = (select max(date_created) from mytable);

Lots of code and what about performance ...

From now on, you can use keep dense_rank for this kind of "problems":

select *
from mytable
where date_created = (select max(date_created) KEEP (DENSE_RANK FIRST ORDER BY status) 
from mytable);

 

This is somewhat weird. We wanted to generate a multi-record module (overflow area below), with on it a multi-line text item in the context, with a height of 4. Like this:

multi-rec, multi-line text item on tabpage

But, what Oracle Designer produces is this:

faulty multi-rec, multi-line text item on tabpage

We tried a lot, but nothing worked resulting in a post-generation step, and I hate post-generation...

Luckely I found a solution. Just add a sub component (use the same window) to the module component without table usage or anything, just a sub-component. Optionally you can change the block navigation (runtime), because Designer now generates a multi-region block with the default - single-record - navigation (change block) and we want multi-record navigation (change record). That's it.

 

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