Hi,

This is a theory newsgroup, so we don't usually discuss that sort
of thing. You'd be better off asking mysql questions in a mysql
forum.

But since you're here, I'll tell you
1) It's quite easy to do it in two queries:
  select count(*) from Table where opened != '0000-00-00';
  select count(*) from Table where closed != '0000-00-00';

2) It's possible to do with one query, but it's more than
twice as complex as the individual queries:
  select
    sum(case opened
      when '0000-00-00' then 0
      else 1
    end) as opened,
    sum(case closed
      when '0000-00-00' then 0
      else 1
    end) as closed
  from Table;

3) No, you don't need to make a separate table

You might need to tweak the above SQL; I just typed it in
and didn't test-execute it. Maybe some tweaking to do to get
the date literals correct.

HTH

Marshall

PS. MySQL has extensive online documentation.

http://dev.mysql.com/doc/mysql/en/index.html

Try this:

select
   count (all opened) as opened,
   count (all closed) as closed
from your_table;

This should do what you want, provided that MYSQL accepts this construct,
treats the "all" keyword the same way other systems do, and recognizes the
dates that are all zeroes as "missing data", better known as NULL.