Using JavaScript To Perform A Task Traditionally Solved With Server-Side Scripting
Asked recently on Yahoo! Answers:
Does anyone know how to automatically update a birthday list on a web page?
Our web page has a section that displays all staff birthdays for the week. This section is updated manually every Monday morning. Is there a way to have this update done automatically everyday. Must display all birthdays for that day and all birthdays for the next 6 days. The format required is:
Date (eg: 13 May)
Name Surname, Department (a new line entry for each employee with a birthday on that day)
Above repeated for each of the other 6 days.
This question presents me with an excellent opportunity to discuss a topic I’ve not really had a chance to broach before: namely, the decision process on whether to use JavaScript or a server-side scripting language, such as PHP or ASP.NET, to accomplish a given task.
Using JavaScript to accomplish a traditional server-side scripted, data-driven task is becoming increasingly popular, especially as ECMAScript standards are more widely adopted, libraries such as jQuery gain prevalence and supporting technologies, such as Google Gears, remove many of the traditional roadblocks in writing client-side scripts for stateless Web applications.
In this case, we have a problem that can be solved either client-side (JavaScript) or server-side (in this case, PHP / MySQL). Which to choose is largely a function of scale: If we’re dealing with hundreds or thousands of employee birthdays we want to display, we’re probably best off using a server-side technology; but if we have fewer employees, it might make sense to simply use JavaScript, and push the workload from the server and onto our visitors.
I’ll demonstrate both the traditional PHP / MySQL approach, as well as a JavaScript approach.
The Trouble With PHP’s Weak Data Types: An Example Examined And Explained
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 »
The Difference Between Null, Empty And Zero-Length Data / Strings
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 »
