ID,21,11814,1,11989,150,Y,10/25/2012 11:36:25 AM,TEST 

"ID",22,11814,1,11989,150,Y,10-25-2012 11:36:25 PM,TEST
[download]

ID,21,11814,1,11989,150,Y,2012-10-25-11.36.25.0000, TEST 

ID,22,11814,1,11989,150,Y,2012-10-25-23.36.25.0000, TEST
[download]

I took up the challenge to do this as a perl one liner, but this version is much easier to understand and build on in the future:

use Date::Manip;
use Text::CSV;
my $csv = Text::CSV->new;
while (<>) {
    $csv->parse($_);
    my @f = $csv->fields;
    $f[7] = UnixDate $f[7], "%Y-%m-%d-%H.%M.%S.0000";
    $csv->combine(@f);
    print $csv->string . "\n";
}
[download]

Output:

ID,21,11814,1,11989,150,Y,2012-10-25-23.36.25.0000,TEST
ID,22,11814,1,11989,150,Y,2012-10-25-23.36.25.0000,TEST
[download]

* Should note that the example above isn't kosher as per the documentation. It will fail on embedded newlines and isn't Unicode friendly. Best to consult that documentation if this is anything other than a one-off.

• perlintro
• QandASection: dates and times

Here is a simple regular expression to convert a string

while (<DATA>) {
    s/(\d+)\/(\d+)\/(\d+)\s+(\d+):(\d+):(\d+)\s+(PM|AM)/$3.'-'.$1.'-'.
+$2.'-'.($7 eq 'PM'?($4+12):$4).'.'.$5.'.'.$6.'.0000'/ge;
     print $_;
}

__DATA__
ID,21,11814,1,11989,150,Y,10/25/2012 11:36:25 AM,TEST
ID,22,11814,1,11989,150,Y,10/25/2012 11:36:25 PM,TEST
[download]

Output:
ID,21,11814,1,11989,150,Y,2012-10-25-11.36.25.0000,TEST
ID,22,11814,1,11989,150,Y,2012-10-25-23.36.25.0000,TEST