如果在mysql / php中未将单元格设置为null,则仅回显

I want to only display an echo statement if a cell is not set to null. I have the following code but keep getting an "HTTP ERROR 500" error when rendering my page since including this conditional statement.

$res=mysql_query("SELECT * from Stores");

<p class="description"><?php echo $row["Address1"];?><br />
<?php
$test=$row["Address2"];
if (isset($test)) {
echo $row["Address2"]<br />;
}?>
<?php echo $row["City"];?>, <?php echo $row["State"];?> <?php echo $row["Zip"];?></p>

I have also tried

if($row["Address2"] != NULL) 

as my conditional statement, getting the same error. Can anyone tell me what I am doing wrong?

TIA

This is a syntax error in PHP:

echo $row["Address2"]<br />;

You forgot to enclose the HTML string in quotes:

echo $row["Address2"] . "<br />";

Also, $row is not being populated, so even if you fix the typo, it won't work for other reasons.