in reply to List columns for a MySQL table

  # loop through ref and extract only the column name
  my @cols;
  foreach my $i (0..$#{$ref})
  { push(@cols, $ref->[$i]->[3]); }

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Any time you're taking an array, and creating another array based on values from it, you should think about using map, rather than an initialize & push in a foreach loop:

my @cols = map { $_->[3] } @$ref;

In Section Cool Uses for Perl