I might do things a little differently, but this will generally do what you need from an algorithmic stand point. There are two syntax errors in your code:

1. In a normal for loop, your list has to be delimited by parentheses. See Foreach Loops in perlsyn.
2. You use both $dbh and $db for your database handle. Without strict, this would have given you a confusing error. See Use strict warnings and diagnostics or die or The strictures, according to Seuss.

You might also benefit from a read through Basic debugging checklist. In the end, your code might look something closer to

#!/usr/bin/perl
use DBI;
use strict;
use warnings;
use diagnostics;

# create database connection
my $dbh = DBI->connect("DBI:mysql:database=somedb;host=localhost",
                       "user",
                       "pass",
                       {    'RaiseError' => 1,
                            'AutoCommit' => 0,
                        },
                       );

# trap errors using eval{}
my $insert_sth = $dbh->prepare("insert into table (field) values(?)");
eval {
    
    #go around some loop to get a value
    for (1...100000) {
        $insert_sth->execute($_);
   }
  
    # commit changes
    $dbh->commit();
};

# any errors
# rollback
if ($@) {
    print "Transaction aborted: $@";
    $dbh->rollback();
}

# close connection
$dbh->disconnect();
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