在 SQL 中选择不同？

Question

The select distinct not working and the count(*) is not selecting the number of grouped rows but it is selecting the duplicate msg_contents.Please help.. I wanted to select distinct username and the number of duplicate usernames.

<?php
require_once"cnc.php";

$sort = "SELECT hate_p FROM hate_t";
$qry = mysql_query($sort);
while($fet = mysql_fetch_assoc($qry)) {
    if($fet == 0) {
        echo "No Entries";
    } else {

        $sql = mysql_query("
            SELECT DISTINCT
                username,
                msg_content,
                COUNT(*) c
            FROM messages
            WHERE msg_content LIKE '%".$fet['hate_p']."%'
            GROUP BY username HAVING c>0"
        );

        while($messages = mysql_fetch_assoc($sql)) {
        ?>
        <tr>
            <td><?php echo $messages['username'];?></td>
            <td><?php echo $messages['c'];?></td>
        </tr>
        <?php
        }
    }
}
?>

Answer 1

you don't need distinct in this case, you can use group by only, distinct get all rows with distinct all columns you select (username,meg_content,count):

SELECT username,msg_content,COUNT(*) c
FROM messages WHERE msg_content LIKE '%".$fet['hate_p']."%'   
GROUP BY username,msg_content 
HAVING c>0

Answer 2

remove msg_content from distinct? you already have it. and @gouda is right, you probably don't need the distinct at all.