$dbh->{AutoCommit} = 0; #DO NOT USE THIS LINE
#  $dbh->begin_work;  #USE THIS LINE

##</code><code>##

$dbh->do("DROP TABLE IF EXISTS $tablename"); #ADDED THIS
$stmt = "CREATE TABLE IF NOT EXISTS $tablename.....

##</code><code>##

use SQL::Abstract;
use Data::Dumper;

use DBD::SQLite;
use Test::More;
use Data::Dump qw(pp);

use strict;
use warnings;

my $tablename = 'atable';
my $dbfile = 'tmp.sqlite';
if (-e $dbfile) 
{ 
   unlink $dbfile 
           or die "delete of existing $dbfile failed $!";
}    

my %attr = ( RaiseError => 1);  #auto die with error printout
my $dbh = DBI->connect("dbi:SQLite:dbname=$dbfile","","",\%attr)
    or die "Couldn't connect to database $dbfile: " . DBI->errstr;

create_test_table( $dbh, $tablename);
print "Original Test Table Contents...\n";
dump_test_table ( $dbh, $tablename);

###  TEST 1 ###
my $WHERE = undef; # (c3 = 'c') OR (c3 = 'ccc')
db_modify_column_value(
  $dbh,
  $tablename,
  [qw/c1 c2/], # the columns to modify with below sub
  sub {
         my ($href, $colnames) = @_;
         foreach (@$colnames)
         {
            $href->{$_}= uc ($href->{$_});
         }
       },  
  $WHERE
);
print "First Test Without a Where Clause...\n";
print "Test Table after modifications to cols c1 and c2....\n";
dump_test_table ( $dbh, $tablename);

### TEST 2 ###

create_test_table( $dbh, $tablename);
print "Second Test mods to c1 and c2 WHERE (c3 = 'c') OR (c3 = 'ccc')\n";

$WHERE = "WHERE (c3 = 'c') OR (c3 = 'ccc')";
db_modify_column_value(
  $dbh,
  $tablename,
  [qw/c1 c2/], # the columns to modify with below sub
  sub {
         my ($href, $colnames) = @_;
         foreach (@$colnames)
         {
            $href->{$_}= uc ($href->{$_});
         }
       },  
  $WHERE
);

print "Test Table after modifications....\n";
dump_test_table ( $dbh, $tablename);


#### subs #######
##

sub db_modify_column_value{
   my ($dbh,$tablename,$col_arrayref,$exe,$WHERE)=@_;
  
   my $result= fetchrows_subset_of_table($dbh,$tablename,$WHERE);
  
   my $updateSQL = "UPDATE $tablename SET ".join("=?,",@$col_arrayref)."=?"." WHERE rowid =?";
   # print "$updateSQL\n";
   my $update = $dbh->prepare($updateSQL);
  
   $dbh->begin_work;
   foreach my $row_hash_ref (@$result){
      $exe->($row_hash_ref,$col_arrayref);
      $update->execute(@$row_hash_ref{@$col_arrayref},$row_hash_ref->{rowid});
   }  
   $dbh->commit;
}


sub create_test_table {
  my ($dbh, $tablename ) = @_;
  
  my @tabledata = (
    {'c1' => 'a', 'c2' => 'b', 'c3' => 'c'},   
    {'c1' => 'aa', 'c2' => 'bb', 'c3' => 'cc'},
    {'c1' => 'aaa', 'c2' => 'bbb', 'c3' => 'ccc'},
    # replicate a row
    {'c1' => 'A', 'c2' => 'B', 'c3' => 'c'},
  );
  
  $dbh->do("DROP TABLE IF EXISTS $tablename");
  $dbh->do("CREATE TABLE IF NOT EXISTS $tablename (c1 TEXT, c2 TEXT, c3 TEXT);");
  
  my $insert = $dbh->prepare("INSERT INTO $tablename (c1,c2,c3) VALUES (?,?,?)");

  $dbh->begin_work;
  for my $rowref (@tabledata){
     $insert->execute(@$rowref{qw(c1 c2 c3)});   
  }
  $dbh->commit;
}

sub dump_test_table{
   my ($dbh, $tablename)=@_;
   my $result = fetchrows_subset_of_table ($dbh,$tablename);
   print "Dumping Current Values in $tablename\n";
   pp $result;
}


## fetchrows_subset_of_table()
#  returns a ref to array of hashref of subset of a table
#  specified by an SQL WHERE clause

sub fetchrows_subset_of_table {
  my ($dbh, $tablename, $WHERE) = @_;
  $WHERE //= '';
  
  my $results = $dbh->selectall_arrayref(
      "SELECT rowid, * FROM $tablename $WHERE ORDER BY rowid",
      { Slice => {} }
  );
  return $results;  # $results is a ref to an array of hash ref's
}

__END__

Original Test Table Contents...
Dumping Current Values in atable
[
  { c1 => "a", c2 => "b", c3 => "c", rowid => 1 },
  { c1 => "aa", c2 => "bb", c3 => "cc", rowid => 2 },
  { c1 => "aaa", c2 => "bbb", c3 => "ccc", rowid => 3 },
  { c1 => "A", c2 => "B", c3 => "c", rowid => 4 },
]
First Test Without a Where Clause...
Test Table after modifications to cols c1 and c2....
Dumping Current Values in atable
[
  { c1 => "A", c2 => "B", c3 => "c", rowid => 1 },
  { c1 => "AA", c2 => "BB", c3 => "cc", rowid => 2 },
  { c1 => "AAA", c2 => "BBB", c3 => "ccc", rowid => 3 },
  { c1 => "A", c2 => "B", c3 => "c", rowid => 4 },
]
Second Test mods to c1 and c2 WHERE (c3 = 'c') OR (c3 = 'ccc')
Test Table after modifications....
Dumping Current Values in atable
[
  { c1 => "A", c2 => "B", c3 => "c", rowid => 1 },
  { c1 => "aa", c2 => "bb", c3 => "cc", rowid => 2 },
  { c1 => "AAA", c2 => "BBB", c3 => "ccc", rowid => 3 },
  { c1 => "A", c2 => "B", c3 => "c", rowid => 4 },
]