How to prevent echoing same value twice in php - php

Question

So I have this drop down list in my form which pull "tags" from database as value for drop down options:
<select name="cartags">
<?php $result = mysql_query("SELECT * FROM Products WHERE ID > '0'");
while($row = mysql_fetch_array($result))
{
echo "<option value=\""; echo $row['Tag']; echo "\""; echo ">"; echo $row['Tag']; echo "</option>";
}
?>
</select>
What is my problem? My problem is that I am adding a lot of products into my databas and my code make dropdown list with tags for all this producst even if they have same tag. So what I need is solution how to prevent that same tag appear twice in my drop down.
I am pretty new to PHP and this is my first question here so I really hope that I explained my problem well.
Thanks in advance!

Answer 1

What is the purpose of WHERE ID > '0'? If ID is an auto-increment then it will always be positive. If not, it should be.
Why are you using mysql_fetch_array and then only using the associative keys? You should use mysql_fetch_assoc instead.
Why are you using a new echo every time you want to output a variable? Just concatenate.
Why are you setting the same string in value as the option's text? Without a value, it defaults to the text anyway.
Why are you not using backticks around your column and table names?
Try this instead:
<select name="cartags">
<?php
$result = mysql_query("SELECT DISTINCT `Tag` FROM `Products`");
while(list($tag) = mysql_fetch_row($result)) {
echo "<option>".$tag."</option>";
}
?>
</select>

Answer 2

Try this
<select name="cartags">
<?php $result = mysql_query("SELECT Tag, COUNT(Tag) tg Products WHERE ID > '0' GROUP BY Tag HAVING COUNT(Tag)>0 ORDER BY tg DESC");
while($row = mysql_fetch_array($result))
{
echo "<option value=\""; echo $row['tg']; echo "\""; echo ">"; echo $row['tg']; echo " </option>";
}
?>
</select>
It will also display the top tags that have the most first.