Limiting Output Part 2

Sharif

Okay, I know I asked this before, got the perfect answer but my curious brain wanted to tweak it more. This code outputs the date from a date field in my database:
<?php
$display_date = mysql_query("SELECT date_FORMAT(date,'%m/%d/%Y') AS date FROM news WHERE id=$id")
or die ("MySQL Error");
if (mysql_num_rows($display_date) > 0)
{
while ($row = mysql_fetch_array($display_date))
{
$news_date = $row["date"];
echo ("News: $news_date");
};

}  
else 
{
	echo("OOX ERROR: Bad Link");
}

Let me fill you in, a user gets to a page titled news.php via a link that would be like this for example: http://domain.com/news.php?id=25. The code checks if the id=25 exists in the database, if it does, it goes on as normal. But what if the id variable was never mentioned in the hyperlink? All the user would get is a blank page... PHP dillema: Page in Distress. This is where you come in... HELP! How would I fix this? How would I display an error if an ID wasn't specified? Do you get me?

laserlight

<?php
if (isset($id) && is_numeric($id))
{
	$display_date = mysql_query("SELECT date_FORMAT(date,'%m/%d/%Y') AS date FROM news WHERE id=$id")
		or die ("MySQL Error");
	if (mysql_num_rows($display_date) > 0)
	{ 
		while ($row = mysql_fetch_array($display_date)) 
		{ 
			$news_date = $row["date"]; 
			echo ("News: $news_date"); 
		}
	} 
	else 
	{ 
		echo("OOX ERROR: Bad Link"); 
	}
}
else
{
	echo("Error: id not specified");
} 
?>

of course, you might want to use $GET['id'] or assign $id to $GET['id']

Sharif

Do you know how beautiful you are? Do you know what a genius you are? Thank the lord multiple times for you... WHOO IT WORKED!!!

Sharif

Whoa but wait: I had a brain blast and decided to tweak it more: How can I do this: If no ID is specified, display one error message, BUT - If an ID is specified but does not exist in the database, display a different message... Lets see who gets that - you get it - you get 100pts.

laserlight

um, your code already does that.

all I did was add a check to ensure that the variable existed and was in numeric form.

Sharif

It does? I'm not so familiar with the isset stuff yet, only on the 40th page of my PHP book 🙂. So which else statement outputs the error message that the ID isn't specified, and which one outputs that it doensn't exist in the database?

laserlight

Well, if the row corresponding to the given id doesnt exist, "OOX ERROR: Bad Link" will be output.

Sharif

Oh ok,

So the ELSE statement INSIDE the IF statement is output if the ID does not exist, and if the ID isn't specified then it displays the other ELSE statement. Thanks for all your help.