How Do You Get One Variable to Show in Place of Another if the First is Null?

How can I get a variable from another table to show in place of a first variable if the first variable is NULL? Basically, I want (see below) the coupon_code variable to show unless it is NULL, in which case I want the offer_instructions variable to show.

I've already tried the code below, and it seems to work. However, I'm sure it's incorrect. All I done was put the two variables side-by-side.

Any help, however small, will be awarded with reputation points!

--------------------------

<?php

$con = mysql_connect("localhost", "root");

if (!$con)

{
die('Could not connect: ' . mysql_error());
}

mysql_select_db("ctyi", $con);

$result = mysql_query("SELECT Coupon_Table.offer_anchor_text, Coupon_Table.offer_url, Coupon_Table.coupon_code,
Offer_Instructions_Table.offer_instructions FROM Coupon_Table, Offer_Instructions_Table WHERE Coupon_Table.offer_instructions_id=Offer_Instructions_Table.offer_instructions_id");

while($row = mysql_fetch_array($result))

{
echo "<table border=\"0\">";
echo "<tr>";
echo "<td><a href=\"" . $row['offer_url'] . "\">" . $row['offer_anchor_text'] . "</a><br />"
. $row['coupon_code'] . $row['offer_instructions'] . "</td>";
echo "</tr>";
echo "</table>";
}

mysql_close($con);

?>

 

Can't you just add an if statement? Like

if (!empty($row['coupon_code']))
echo $row['coupon_code'];
else
echo $row['offer_instructions'];

 

<?php

$con = mysql_connect("localhost", "root");

if (!$con) die('Could not connect: ' . mysql_error());

mysql_select_db("ctyi", $con);

$query = <<<QUERY
select
    coupon.offer_anchor_text,
    coupon.offer_url,
    coupon.coupon_code,
    instructions.offer_instructions
from
    coupon_table as coupon,
left join
    offer_instructions_table as instructions on
    instructions.offer_instructions_id = coupon.offer_instructions_id
QUERY;

$result = mysql_query($query);

while ($row = mysql_fetch_array($result)) {
    $offerText = ($row['coupon_code'] != '') ? $row['coupon_code'] : $row['offer_instructions'];
    
    $output[] = "<table border=\"0\">";
    $output[] = "<tr>";
    $output[] = "<td><a href=\"{$row['offer_url']}\">{$row['offer_anchor_text']}</a><br />{$offerText}</td>";
    $output[] = "</tr>";
    $output[] = "</table>";
}

mysql_close($con);

PHP:

 

Thanks, guys! As promised, I have added reputation points to both of you.

Ahowell, your method looked cool but didn't work, dude. It gave an error message, even with the PHP tag closed.

Wdillsmith, your method worked, but only after I adapted it a bit (see below).

Please tell me, guys . . .

Should I use this code? Is it wise to put an If statement inside a While loop? Would you guys use it? If not, how would you change it?

<?php

$con = mysql_connect("localhost","root");

if (!$con)

{
die('Could not connect: ' . mysql_error());
}

mysql_select_db("ctyi", $con);

$result = mysql_query("SELECT 

Coupon_Table.offer_anchor_text, 
Coupon_Table.offer_url, 
Coupon_Table.offer_expiration_date,
Coupon_Table.coupon_code, 

Advertiser_Table.advertiser_logo,
Advertiser_Table.advertiser_name,
Advertiser_Table.advertiser_url,

Category_Table.category_name,
Category_Table.category_url,

Offer_Instructions_Table.block_anchor_text,
Offer_Instructions_Table.offer_instructions

FROM Coupon_Table, Advertiser_Table, Category_Table, Offer_Instructions_Table
WHERE Coupon_Table.advertiser_id=Advertiser_Table.advertiser_id
AND Coupon_Table.category_id=Category_Table.category_id
AND Coupon_Table.offer_instructions_id=Offer_Instructions_Table.offer_instructions_id");

while($row = mysql_fetch_array($result))

	{
	echo "<table border=\"0\">";
  	echo "<tr>";
 	echo "<td><img src=\"" . $row['advertiser_logo'] . "\" alt=\"\" /></td>";
  	echo "<td><a href=\"" . $row['offer_url'] . "\">" . $row['offer_anchor_text'] . "</a><br />";
	[B]if (!empty($row['coupon_code']))
	{echo $row['coupon_code'];}
	else {echo $row['offer_instructions'];}[/B]
	echo "<br /> Offer expires: " . $row['offer_expiration_date'] . "<br />";
        echo "About <a href=\"" . $row['advertiser_url'] . "\">" . $row['advertiser_name'] . "</a><br />";
 	echo "Category: <a href=\"" . $row['category_url'] . "\">" . $row['category_name'] . "</a></td>";
	echo "<td><a href=\"" . $row['offer_url'] . "\">" . $row['block_anchor_text'] . "</a></td>";
	echo "</tr>";
	echo "</table>";
  	}

mysql_close($con);

?>

Code (markup):

 

I would have made it a set variable just so the code looks neater. But it shouldn't really matter. Your going to need the IF statement inside the loop as each loops checks a different row in the sql db.

<?php

$con = mysql_connect("localhost","root");

if (!$con)

{
die('Could not connect: ' . mysql_error());
}

mysql_select_db("ctyi", $con);

$result = mysql_query("SELECT 

Coupon_Table.offer_anchor_text, 
Coupon_Table.offer_url, 
Coupon_Table.offer_expiration_date,
Coupon_Table.coupon_code, 

Advertiser_Table.advertiser_logo,
Advertiser_Table.advertiser_name,
Advertiser_Table.advertiser_url,

Category_Table.category_name,
Category_Table.category_url,

Offer_Instructions_Table.block_anchor_text,
Offer_Instructions_Table.offer_instructions

FROM Coupon_Table, Advertiser_Table, Category_Table, Offer_Instructions_Table
WHERE Coupon_Table.advertiser_id=Advertiser_Table.advertiser_id
AND Coupon_Table.category_id=Category_Table.category_id
AND Coupon_Table.offer_instructions_id=Offer_Instructions_Table.offer_instructions_id");

while($row = mysql_fetch_array($result))

	{

	[B]if (!empty($row['coupon_code'])) {
	$var = $row['coupon_code'];
	}else{
	$var = $row['offer_instructions'];
	}[/B]

	echo "<table border=\"0\">";
  	echo "<tr>";
 	echo "<td><img src=\"" . $row['advertiser_logo'] . "\" alt=\"\" /></td>";
  	echo "<td><a href=\"" . $row['offer_url'] . "\">" . $row['offer_anchor_text'] . "</a><br />";
	[b]echo $var;[/b]
	echo "<br /> Offer expires: " . $row['offer_expiration_date'] . "<br />";
        echo "About <a href=\"" . $row['advertiser_url'] . "\">" . $row['advertiser_name'] . "</a><br />";
 	echo "Category: <a href=\"" . $row['category_url'] . "\">" . $row['category_name'] . "</a></td>";
	echo "<td><a href=\"" . $row['offer_url'] . "\">" . $row['block_anchor_text'] . "</a></td>";
	echo "</tr>";
	echo "</table>";
  	}

mysql_close($con);

?>

Code (markup):

 

Actually, there's a method to do this in a single line.

echo (empty($row['coupon_code']) ? $row['offer_instructions'] : $row['coupon_code']);

PHP:

 

Nabz245 and Shoro, thank you both! I have added reputation points to both of your accounts.

Shoro, cool response, dude!