To be honest, I don't quite understand your request.

You want to loop over your query results and push each column's value into a seperate array?

So the solution should be to push them into an Hash of Arrays (HoA) like this:

# untested
my %results;
while (my $data = $sth->fetchrow_hashref()) {
    while (my($k, $v)= each %$data) {
        push( @{$results{$k}}, $v );
    }
}
# your dataplot should then go like this:
@data_to_plot = ( [ @results{qw/dayofweek canning multipack quest/} ] 
+);
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