Select Records From MySql on PHP

I have a table with records like this

country_name   username
------------------------
India          abc1
Austra开发者_如何转开发lia      abc2
India          abc3
USA            abc4
Australis      abc5
Lebanon        abc6

From Above Table I need to get country list without repeat, is there any chance to get like this...

Ex Code:

$sql = 'bla bla bla bla bla';
$res = mysql_query($sql);

while($row = mysql_fetch_array($res)){
    echo $row['country_name'].'<br /><br />';
}

Ex Output(Like this):

India
Australia
USA
Lebanon

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Try this:

SELECT DISTINCT country_name FROM table

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The group by method is better if you want to select more than just the country name with your query...like: $sql = "SELECT country_name, username FROM table GROUP BY country_name;

but if you just want to select country name, DISTINCT is slightly faster.

$sql = "SELECT DISTINCT country_name FROM table";