Remove Duplicated from results - php

Question

I've got a database and I'd like to show some results from it without getting duplicates
Example
<?php
$sql = "select * from my_table order by subcategory ASC";
$result = mysql_query($sql) or die($qry);
if (mysql_num_rows($result) == '0') {
echo "No subcategory";
} else {
while ($line = mysql_fetch_array($result)) {
echo $line[subcategory];
echo "<br>";
}
}
?>
It currently shows me all subcategories even if they are duplicated
Question: How i can filter the results so that it will only show a subcategory once even if it's in there 4 times.
Do I need to add something to this code to shows only without duplicated?
$sql ="select * from rss order by subcategory ASC";

Answer 1

You can use DISTINCT in your SQL, to avoid getting duplicates back from the database, like this:
select distinct * from my_table order by subcategory ASC

Answer 2

Use GROUP BY
$sql = "select subcategory from rss group by subcategory"
See the manual for more information: http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html

Answer 3

Look into SELECT DISTINCT and GROUP BY

Answer 4

select * from rss order by subcategory ASC
First of all it is a good practive to expand wildcard. List all of the columns instead of using *
There are two approaches on what you're trying to achieve depending on what you need:
Select distinct column1,column2 from rss order by subcategory desc
select max(column1), max(column2), subcategory from rss order by subcategory desc group by subcategory

Answer 5

use continue; keyword and check for duplicates in your while loop
<?php
$sql = "select * from my_table order by subcategory ASC";
$result = mysql_query($sql) or die($qry);
if (mysql_num_rows($result) == '0') {
echo "No subcategory";
} else {
while ($line = mysql_fetch_array($result)) {
if ($dupes[$line['subcategory']])
continue;
$dupes[$line['subcategory']]++;
echo $line['subcategory'];
echo "<br>";
}
}
?>
or just use distinct
$sql ="select distinct * from rss order by subcategory ASC";

Answer 6

You should take a look at array_unique(). Use it to remove all duplicates from the array.