Waxing Cerebral

What I use on xubuntu linux for specific tasks:....

Task	Tool	Date	Ubuntu Package	Comment
pdf annotating	flpsed	Sep 2008	flpsed	Very basic app that enables load/save of ps and pdf. Multi-line text can be added to the docs. No highlighting option or editing of existing content.
pdf editing	pdfedit	Sep 2008	pdfedit	Allows editing of any part of multi-page PDF documents. Can be very slow to use on long documents. New content such as highlighting and single-line text can be added also.
vector graphics / single-page pdf annotating	inkscape	Sep 2008	inkscape	Great tool for vector graphics, quick and easy results. Can import a single page of PDF documents.
xml viewing / formatting	XML Copy Editor	Sep 2008	xmlcopyeditor	Load and view xml. Validate form and against dtd etc, plus nicely format. Quick and easy.
diff	meld	Sep 2008	meld	Excellent visual diff/merge tool.
text/source editor	SciTE	Sep 2008	SciTE	Excellent text editor with awareness of many languages and markups. Tabbed view.

Ah ha! Sound confusing? Why yes it is.

Turns out that SQL (and HQL for that matter) don't allow regular operators to run against a null field. Fair enough, it means:

will evaluate to false if the id is null, so rows with null values won't be returned. Ok.

However, where it gets tricky is in NOT clauses, which also won't return if the value is null. If an operator (other than is null or is not null) is used on a null field, SQL evaluates it to null, which the where clause in turn evaluates to false. So...

will return rows where id is: 1, 2, 3, 4, 5, 7, 8 etc...
but NOT where id is: 6 or null

The way around it? If the field you are 'NOT' selecting on can be null, then you must include a 'is null' OR match:

I often write little javascript scripts to get a job done on the web, and usually using greasemonkey. So, to keep track of the little useful tidbits that I tend to forget cos I use them so infrequently, I'll keep this post updated with them as I remember/come across them.

Adding elements to html

Working with greasemonkey

Greasemonkey differs from writing a script that loads with the page, as actions that you define don't implicitly have access to the functions within the greasemonkey script. So setting up things like onclick won't work. My solution to this used to be to add a script element (defining my functions) to the page using addelement. While this worked, it was very messy and hard to maintain. Here's a much better solution, which involves using an event listener rather than just defining onclick (for example).
This is from consuming experience:
In the orignal html page

So our greasemonkey script contains

and then anywhere in the greasemonkey script we can define myFunction