PHP Filter FILTER_VALIDATE_URL Limitations

8th April 2008

I have previously talked about the filter functions available in PHP5, but failed to spot this limitation when I was doing the research for those articles. It appears that the filter to validate URL string, namely FILTER_VALIDATE_URL, is not really adequate to the task.

Take the following examples of the filter in an if statement.

Capture A Website As Image With PHP

7th April 2008

One thing that comes in useful when linking to other websites is to use a little thumbnail of the site as part of the link. Although it is possible to do this it usually involves having command line access to the server so that you can install various different programs and extensions.

The simplest mechanism accomplish this is to use third party sites to create the thumbnail for you. Here are a few examples of free thumbnail services.

Update Or Insert A Row With MySQL And PHP

Many situations arise where you need to either insert or update some data in a table but which you will not be certain as to which function to perform. A common solution is to do a query on the table first to see if the data exists and then insert if it doesn't and update if it does. However, this creates an unnecessary overhead in that every time the code is run at least 2 queries are run.

philipnorton42 Sun, 04/06/2008 - 12:10

Random Number Range In MySQL

5th April 2008

To create a number between one value and the next you can use the following formula, where i is the lower end of the range and j is the higher end of the range.

FLOOR(i + RAND() * (j – i))

Rather than put in (j-i) in your query you should put in the result. So for a number between 1 and 10 you would make i = 1 and j = 11. 11-1 = 10 so the query would run like this.

Latest MySQL Errors With PHP

Pinpointing where an error in a program is occurring is not always easy. This can be even more of a problem when you write an SQL query that produces an error. Take the following select statement, which is clearly wrong.

philipnorton42 Fri, 04/04/2008 - 09:48

HTML Checkbox To PHP Array

3rd April 2008

To create a simple HTML check box use the following bit of code.

<input type="checkbox" name="option2" value="Milk" />

To set the checkbox as filled in include a checked attribute. To make the control XHTML compliant you will need to do the following.

Creating A 404 Page In PHP

2nd April 2008

Setting up a 404 page on your site will help users when they navigate to a page that doesn't exist. Rather than dropping them into a scary server message you can give them a nice friendly error page. The first step is to make sure that if the user generates a 404 error they are given a nice page. Add this line to your .htaccess file.

Array Sorting Algorithms In PHP

1st April 2008

There are many ways to sort an array in PHP, the easiest being to use the sort() function built into PHP. This sort function is quick but has it's limitations, especially when sorting things like dates as PHP usually guesses which value is higher than the other and can produce odd results. However, there are plenty of sorting algorithms available than can allow you to sort an array in any way you want.

The simplest of these is called the bubble sort. Here is a function that will sort an array of values using the bubble sort algorithm.