To include a JavaScript file into a HTML page you can use the script tag with the src parameter pointing towards the source code file. However, there is a subtle difference between the script tag in HTML and XHTML. This is because the language attribute is not supported in XHTML, so if you just copy the code from HTML to XHTML the page won't validate. The solution here is to just leave it out.

For HTML

Getting a random row from a MySQL table requires the use of the RAND() function in the ORDER BY clause of the SELECT statement. This will generate a new random number for each row and order them by that new number. In order to get a single row this is combined with the LIMIT clause to limit the result to a single row.

To round a number in PHP you can use one of three functions, these are round(), ceil() and floor(). All of these functions take number as the input and will round the value depending on the function used.

To round to the closest integer use the round() function.

The is_numeric() function in PHP can be used to see if a number contained in a string is numeric. The function returns true is the variable can be parsed into a string, otherwise it returns false. Here are some examples:

Here is a function to generate a select box for a HTML form. The three parameters are:

When debugging PHP code the print_r can be useful if you want to know what an array or object contains. It will take any variable as input and will print off as much information as it can about that variable. The following code.