$q .= '%';

## query 1
my $sql = qq{
	SELECT a, b, c
	FROM t 
	WHERE Lower( a ) LIKE '$q'
};
my $sth1 = $dbh->prepare($sql);
$sth1->execute();

## query 2
my $sth2 = $dbh->prepare(qq{
	SELECT a, b, c
	FROM t  
	WHERE Lower( a ) LIKE ?
});
$sth2->execute($q);