When you do a date comparison with DateTime.Now using LINQ-to-Entities against a SQL Server database, the engine translates DateTime.Now to GetDate().

For example:

var items = (from t in context.Token
             where t.Expiry > DateTime.Now).ToList();

will ultimately generate SQL that says:

...
WHERE Token.Expiry > GetDate()
...

This can cause some significant (and subtle) problems:

If the application running this code is on a different server to the SQL database, any time differences can break code.

This is what happened to me.  There was a one minute time difference between the web service running this code and the SQL Server machine.  I was using the Entity Framework to set the expiry date to DateTime.Now.AddSeconds(60), and retrieving it later by comparing it to DateTime.Now.  Despite this, I was effectively setting the expiry using the web server’s time, and comparing it using the SQL Server’s time.

If you’re having a similar problem, I hope you stumble across this post.

I’m using an ASP.Net CMS called Kentico CMS.  It is quite good – much more friendly than some others I’ve used recently.  I’ve been trying to get the CSS Menu control set up so that it will always show root pages, and also the pages beneath the current page.  It wasn’t as easy as I thought.

For example:

Home
About
 - Our Products
 - Our Services
    - Programming
    - Design
Links
 - Friends
Contact

In the example above, no matter where I was on the site, I wanted to see Home, About, Links, and Contact on the menu.  If I was on the About page, then the Our Products and Our Services links should be shown as well.  So I’m looking for the root pages and the children of the current page.  I thought this was pretty standard menu behaviour, but it took me a couple of hours to figure out.

Here’s the solution:

In the design view, edit the properties of the menu by clicking on its gears icon, go to the Content Filter section and put the following query in the WHERE condition field:

NodeAliasPath LIKE ‘{&/{0}/%&}’ OR NOT NodeAliasPath LIKE ‘/%/%’

This gets all items under the current one {0}, or anything that’s not a root element.  You’ll have to make sure the Maximum nesting level is set appropriately, but that’s it.

Hopefully someone else with the same problem will stumble across this and save themselves an hour or two.

Now here’s the point in this post where I really wish I could remember the word I want to use.  You know when you hear about something for the first time in your life, then amazingly you hear about it several times in the next short while?  You wonder how you’re suddenly being bombarded with this new concept when you only just found out about it?  Yeah, there’s a word for that and I’ve forgotten what it is.  That word goes here.

I picked up a Popular Science magazine a few days before I found this Slashdot post and amazingly, there was a whole section in it about “free” energy.  Awesome concept.

There’s a whole host of low-powered devices in common use today, and there’s superfluous energy being expended everywhere.  Surely this energy can be used to power these low-powered devices?

The simplest example in the Popsci magazine was the humble light switch.  When you wire up a house, you have wire for power going to the actual light, as well as wire for control going from the light to the light switch.  When you flick the switch to turn the light on, you’re expending energy.  Not much, granted, put apparently enough to send a wireless signal to the light (or a controller next to it) to tell it to turn on.  With a setup like this, there’s no need for wire to run down the walls to the switches.  Yeah, it’s not much of a power saving and it’s probably not worth the extra initial cost right now, but in the future it could, and combining a few dozen simple ideas like this in every house could surely save some energy.

The fact is, we expend a lot of energy when we do anything.  There’s also ambient energy all over the place – the obvious ones like wind and light, but also vibrations and body heat.  If we could capture a fraction of that energy and put it to use, we’d have much less need for power plants.

There are thousands of options out there.  If you go for a walk, chuck your mobile phone in the little holster on your belt, and as you walk, the up-down motion of your steps can charge it.  Or maybe the energy absorbed when rain lands on your car roof could be enough to power your windscreen wipers.

Perhaps after a time, when it becomes cheap enough, device manufacturers may get into the habit of building these “free” power sources into their devices.  A mobile you didn’t have to plug into a wall or a sound-powered LED light you could just stick onto a ceiling would certainly have a market.

Clearly this stuff interests me.

I’m moving on from my current job.

I won’t delve too deeply into the reasons, but the short version is that I’ve really done all I can for my career at Global MoneyLine at the moment.  I assume it’s the same with most financial institutions, but times are tough and the emphasis is understandably not on exciting new projects and new technologies.  Consequently, I’m not really learning new things and expanding myself any more and for me, that means its time to go.  It will turn around, sure, but I guess I’m just impatient.

So I start my new job with The Systems Works (www.tsw.com.au) on Monday next week.  Excited, anxious, slightly nervous, but very much looking forward to the change.  I’ll keep you posted.

Basically, the premise is that there’s a very common misconception that all programmers are alike and have the same productivity.  It’s definitely worth a read.

While his article focuses on the practice of offshoring programming to cheap overseas countries, the idea is also relevant when talking about hiring new (local) programmers either to replace others or in response to increased workload.

The misconception that all programmers are the same can lead to an almost apathetic approach to hiring by managers.  If someone quits, that’s fine, we’ll just hire another programmer to take over the work.  If there are new requirements that mean we need a new developer, then fine, we’ll just hire another one.  One problem is that there’s usually a significant lead time filled with learning about the project before even the best programmer can be truly productive.  The other problem is that which is outlined in Miano’s article; one programmer can be many times more effective than another.

I’m not sure what the solution to this is.  I’ve preached this line many a time but because it’s in such stark contrast to the person x time = fixed productivity formula that is relatively true for most other professions, it falls on deaf ears.

He’s right about it all of course – an idea by itself it worth nothing.  If you do nothing with it, then you have nobody to blame but yourself if someone else makes a whole lot of money from a similar idea.

Of course this doesn’t necessarily stop the nagging feeling that it could have been you with all that income…

My big idea that I did nothing with?  I think it was around 1998 when I thought it would be useful to have a real estate website to which rental agencies could submit available properties complete with photos and searchable descriptions.  Seriously.  Oh well.

Anyway, it appears that a localisation fault on a mobile phone in Turkey has resulted in two deaths and three jailings.  Warning – bad language in this link!

Wow.  That’s a very bad side-effect…

ramblings of a mid-late 20s IT nerd / volleyball junkie / semi-professional drinker

…how depressing…

Damo