You're already reading the file using DBD::CSV, so reading again w/Text::CSV is redundant. You can (db-independently) get the column names with a SELECT query, and then create another SELECT for the avg's (which you can do in one call). (note: untested) 
my $sth = $dbh->prepare("SELECT * FROM results WHERE 1=0");
$sth->execute;
my @cols = @{$sth->{NAME}};
my $avgSQL =
  'SELECT '
  . join(', ', map { "avg($_) as $_" } @cols )
  . ' FROM results';
my $avgsHashRef = $dbh->selectrow_hashref($avgSQL);
use Data::Dumper;
print Dumper $avgsHashRef;

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Note that in your code $avg = $dbh->prepare(...) line didn't actually execute the code. Simply doing $avg = $dbh->selectrow_array(...) instead work would have done want you intended.

In reply to Re: Database processing by davidrw
in thread DBI::st=HASH output by DrAxeman

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