Remove duplicates in Arrays from MYSQL query and then insert into another table

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 1

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 .

Answer 2

$newArray = array_unique($yourArray);

This will create a new array only with unique values; excluding any duplicates.

Answer 3

You can use group by clause to group the results with the same id, so that you'll get only unique ids

Answer 4

No need to get PHP involved. Just SELECT using GROUP BY .

INSERT INTO subsalerts (memalertid, idMembers, emailid)
    SELECT memalertid, $idMembers, $emailid FROM memlist WHERE listID IN ($idList) AND emailyes = 1 GROUP BY memalertid;