$a = "aaaaa\n";
$a = $a."bbbbb";
$sql="insert into test (field1) value '$a';

produces
insert into test (field1) value 'aaaaa
bbbbb'

what it actually runs is 
insert into test (field1) value 'aaaaa

##</code><code>##

$sql="insert into test (field1) value 'aaaaaaa' + Chr(13) + Chr(10) + 'bbbbbbbb';

##</code><code>##

$a =~ s/chr(13)chr(10)/' + Chr(13) + Chr(10) + '/;