What is the most straightforward way to pad empty dates in sql results (on either mysql or perl end)?

Question

I\'m building a quick csv from a mysql table with a query like:

select DATE(date),count(date) from table group by DATE(date) order by date asc;

Answer 1

Since you don't know where the gaps are, and yet you want all the values (presumably) from the first date in your list to the last one, do something like:

use DateTime;
use DateTime::Format::Strptime;
my @row = $sth->fetchrow;
my $countdate = strptime("%Y-%m-%d", $firstrow[0]);
my $thisdate = strptime("%Y-%m-%d", $firstrow[0]);

while ($countdate) {
  # keep looping countdate until it hits the next db row date
  if(DateTime->compare($countdate, $thisdate) == -1) {
    # counter not reached next date yet
    print CSV $countdate->ymd . ",0\n";
    $countdate = $countdate->add( days => 1 );
    $next;
  }

  # countdate is equal to next row's date, so print that instead
  print CSV $thisdate->ymd . ",$row[1]\n";

  # increase both
  @row = $sth->fetchrow;
  $thisdate = strptime("%Y-%m-%d", $firstrow[0]);
  $countdate = $countdate->add( days => 1 );
}

Hmm, that turned out to be more complicated than I thought it would be.. I hope it makes sense!