如何在获得非重复条目时查询重复条目？

Question

I have a table like this..:

I am trying to figure out how to query only one of the duplicate entries while still getting the non-duplicate entries?

$query = "SELECT id, size, color FROM `".$item."` WHERE size in (SELECT size FROM `".$item."`
                GROUP BY size HAVING COUNT(*)>1)";
$resul = $conn->query ($query);
if($resul->num_rows > 0){
    while($r = $resul->fetch_assoc()){
        echo $r["size"];
    }
}

Answer 1

SQL DEMO

This select the row with biggest id for each size:

SELECT t1.id, t1.size, t1.color 
FROM yourTable t1
LEFT JOIN yourTable t2
  ON t1.id < t2.id
 and t1.size = t2.size
WHERE t2.id IS NULL   // if no one is bigger than you, you are the biggest.

Now you filter the one with more then one row

 AND t1.size ( SELECT size
               FROM yourTable
               GROUP BY size
               HAVING count(*) > 1)