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Multiple nested MySQL functions in PHP?

I was going through code today, trying to make some things more compact. The application worked without problems, so I knew that mysql error statements were superfluous.

This is the type of statement I was changing, I figured that I’d remove the seemingly unnecessary $result2 variable

$result2 = mysql_query($carts) or die(mysql_error());<br />
while ($row2 = mysql_fetch_array($result2)) {<br />
	echo "<option>$row2[0]</option>";<br />
}

so this is what I changed it into (I basically replaced where it said $result2, to what $result2 had contained, and removed the error check)

while ($row2 = mysql_fetch_array(mysql_query($carts))) {<br />
	echo "<option>$row2[0]</option>";<br />
}

but this code returned infinite loops, much to my surprise. Why is it doing this? is there a way around it?

Recently, I wrote about how PHP’s weak data types often can lead to problems for new programmers who don’t understand the difference between null, empty and zero-length variables. Here’s another opportunity to expose why strong data typing is essential for best programming practices, and to show how PHP’s weak data types — normally, a source of comfort for beginning programmers — can be the source of extensive frustration.

Continue reading ‘The Trouble With PHP’s Weak Data Types: An Example Examined And Explained’ »

A common problem faced by new programmers is understanding the difference between null, empty and zero-length variables, especially when working with database records.

While, for most intents and purposes, the three things have the same effect — either you have some data you can work with, or you don’t — they arise from different circumstances. Understanding how null, empty and zero-length are different can help you avoid data errors in your programs.

The short version is this: If a variable simply doesn’t exist — usually because it hasn’t been declared, but sometimes because it hasn’t been assigned a value — it’s null. If the variable exists but contains no data, it’s empty. And if a structured data variable, such as an array, exists but doesn’t contain any items, it’s zero-length.

An analogy is in order.

Think of a database as a house. A house has rooms, and in each of these rooms are furniture and accessories that are appropriate to that room.

For example, the kitchen has a stove, refrigerator and sink. The bedroom has a dresser, bed and armoire. The living room has a couch, television and coffee table.

Continue reading ‘The Difference Between Null, Empty And Zero-Length Data / Strings’ »

I have been working in VBA for Microsoft Office 2007 lately. And if you haven’t used it yet, I can tell you there have been significant changes in macro / VBA security versus Office 2003.

Basically, getting a VBA macro / module that hasn’t been digitally signed to run in Word 2007, Excel 2007 or Access 2007 requires the end user to go through a fairly complicated process — if his network’s group policies even allow unsigned macros to run — with many scary warnings against running unsigned code thrown in for good measure.

So I really needed to get a code-signing cert. And after looking around on the Web for places to get one, I settled on Comodo, via Tucows.

Tucows will sell a Comodo certificate for $75 per year, or $195 for three years — which, while not cheap, is less than half the cost some certificate authorities charge for a one-year cert, and a significant discount over Comodo’s published prices.

There’s not a lot on the Web about the experience and process of getting a certificate from Comodo, so I thought I would share some advice.

Continue reading ‘My Experience Getting A Code Signing Certificate From Comodo’ »