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Recently asked on Yahoo! Answers:

Change image when new option selected in PHP?
This probably will also require Javascript. I am using this code:
What it does is draws from a MySQL database where an “avatars” table is set. The “avatars” table includes fields “id” (INT), “title” (VARCHAR) and “url” (VARCHAR).
Basically, the script draws the rows from the table. It puts the titles in an HTML select form as options.

{code block snipped}

When an option is selected, I would like the image that is selected to be shown, without a new page having to be loaded.

This is very easy to do with JavaScript and DOM manipulation, but based on the user’s code, it requires a bit more work that previous blog entries I’ve made on images and JavaScript.

Let’s start with looking at the original code block.

Continue reading ‘Cleaning Up Some PHP And Incorporating A JavaScript-Based Image Preview’ »

Asked recently on Yahoo! Answers:

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’ »

You’ve probably noticed I’ve been putting in some work on this blog lately.

Amid all the tweaking, one fact became obvious: I was going to need to make significant changes to the TypoXP theme to get it fully compatible with post-WordPress 2.3 releases.

I thought long and hard about that. I really like TypoXP and I wanted to stick with it as long as I could. But the more I thought about it, the more I decided it made sense to move on to a more recent theme.

Once again, it came down to two choices: Barthelme and Fluid Blue. In the end, Bartheme won.

Continue reading ‘Goodbye, TypoXP; Hello, Barthelme; Welcome Back, WP-Syntax; Tag, You’re It’ »

Recently asked on Yahoo! Answers:

How do I read and write binary image data from SQL server?
I’m making a website where visitors can upload their images, I’ve done the uploading code and it (probably) works fine because I can see the data is recorded on the database.

The problem is when I want to test it (display the image on the website) theoretically I have to read the data from the SQL server and write it to the web. I’ve done several ways and tests but all of them failed to display the image.

Anybody knows how to do this? I’m using visual web developer 2008 and VB.NET as programming language

Note: no “wizards” please, I want it to be implemented using fully coded like I did with the uploading code

There are other examples on the Web on how to do this, but most are either written in C#, or are very specific to a given set of circumstances, so I thought I would explore this subject for Visual Basic .NET, and in the process try to address a few different ways to display an image.

The executive summary: Displaying an image that’s stored in a database requires you to make a “helper page.” And that’s what we’re about to make.

Continue reading ‘Displaying An Image Stored In A SQL Server Database On An ASP.NET Page Using VB.NET’ »