Question: I have the code below to query a table which retrieves arrays. The parameter $idList could have several values and may therefore produce duplicates. I am only interested in inserting one unique memalertid.

Any advice on how to remove the duplicates would be much appreciated.

```
$sql = mysql_query("SELECT  memalertid from memlist where listID IN ($idList) AND (emailyes = '1') ");
while ($info = mysql_fetch_array($sql)){
$insert_query = "insert into subsalerts (memalertid, idMembers, emailid) VALUES('".$info['memalertid']."','$idMembers','$emailid')";
$insert_buffer = mysql_query($insert_query);    

```

Thanks very much

Answer: 
Simply use `SELECT DISTINCT` to select distinct rows.

```
SELECT DISTINCT memalertid FROM memlist WHERE listID IN ($idList) AND (emailyes = '1')

```

You could also `GROUP BY memalertid` instead.

```
SELECT memalertid FROM memlist WHERE listID IN ($idList) AND (emailyes = '1') GROUP BY memalertid

```

For more information: <http://dev.mysql.com/doc/refman/5.5/en/select.html>.
You can use [group by](http://dev.mysql.com/doc/refman/5.1/en/select.html) clause to group the results with the same id, so that you'll get only unique ids