$query = "   SELECT field1
                FROM table1
                WHERE field2 IN (1,2,3,4,5) ";

$sth1 = $dbh->prepare($query) or die->$errstr();

$sth1->execute($valuesForIn) or die $dbh->errstr;

##</code><code>##

$query = "   SELECT field1
                FROM table1
                WHERE field2 IN (?,?,?,?,?) ";

$sth1 = $dbh->prepare($query) or die->$errstr();

$sth1->execute(1,2,3,4,5) or die $dbh->errstr;

##</code><code>##

"SELECT * FROM Customers
WHERE Country IN (SELECT Country FROM Suppliers)"