Unrelated to your actual questions, there are two easy things you can improve in your code:

If you're doing an error check after each database operation anyway, you might just as well set the RaiseError => 1 option during connect. That way you save a whole lot of redundant error check code.

if ($mth eq "01") {$monnm = "January"};
if ($mth eq "02") {$monnm = "February"};
if ($mth eq "03") {$monnm = "March"};
if ($mth eq "04") {$monnm = "April"};
if ($mth eq "05") {$monnm = "May"};
if ($mth eq "06") {$monnm = "June"};
if ($mth eq "07") {$monnm = "July"};
if ($mth eq "08") {$monnm = "August"};
if ($mth eq "09") {$monnm = "September"};
if ($mth eq "10") {$monnm = "October"};
if ($mth eq "11") {$monnm = "November"};
if ($mth eq "12") {$monnm = "December"};
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I'd write that as

my @months = qw/January February March April May June July August Sept
+ember October November Decemeber/;
# arrays are zero-indexed, so subtract one to 
# get from the month number to the array index:
$monnm = $months[$mnth - 1];
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