try using :

$dbh->do("use <databasename>") || die("SQL Error: " . $dbh->errstr);
my $log = $dbh->prepare("Insert into fp3 (<fieldname1>,
+ <fieldname2.) values ('$d', '$c')")
    or print "Couldn't prepare INSERT statement: ". DBI->errstr. "\n\n
+";
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instead of prefixing the databasename in the SQL stmt...
hth