Selecting COUNT from different criteria on a table

Question

I have a table named \'jobs\'. For a particular user a job can be active, archived, overdue, pending, or closed. Right now every page request is generating 5 COUNT queries and

Answer 1

This is the typical solution. Use a case statement to break out the different conditions. If a record meets it gets a 1 else a 0. Then do a SUM on the values

  SELECT
    SUM(active_count) active_count,
    SUM(overdue_count) overdue_count
    SUM(due_today_count) due_today_count
  FROM 
  (

  SELECT 
    CASE WHEN jobs.status_id NOT IN (8,3,11) THEN 1 ELSE 0 END active_count,
    CASE WHEN jobs.due_date < '2011-06-14' AND jobs.status_id NOT IN(8,11,5,3)  THEN 1 ELSE 0 END  overdue_count,
    CASE WHEN jobs.due_date BETWEEN '2011-06-14' AND '2011-06-15 06:00:00.000000' THEN 1 ELSE 0 END  due_today_count

    FROM "jobs"
    WHERE
      jobs.creator_id = 5 ) t

UPDATE As noted when 0 records are returned as t this result in as single result of Nulls in all the values. You have three options

1) Add A Having clause so that you have No records returned rather than result of all NULLS

   HAVING SUM(active_count) is not null

2) If you want all zeros returned than you could add coalesce to all your sums

For example

 SELECT
      COALESCE(SUM(active_count)) active_count,
       COALESCE(SUM(overdue_count)) overdue_count
      COALESCE(SUM(due_today_count)) due_today_count

3) Take advantage of the fact that COUNT(NULL) = 0 as sbarro's demonstrated. You should note that the not-null value could be anything it doesn't have to be a 1

for example

 SELECT
      COUNT(CASE WHEN 
            jobs.status_id NOT IN (8,3,11) THEN 'Manticores Rock' ELSE NULL
       END) as [active_count]