Question

I have this simple query:

Select 
To_Date('2012-sep-03','yyyy-mon-dd')as Date_Of_Concern,
Count(Player_Id) as Retained
From Player
Where
(To_Date('2012-sep-03','yyyy-mon-dd')-Trunc(Init_Dtime))<=7

Which Results In:

Date_Of_Concern         Retained
 03-Sep-12               81319

This query counts all of the players in my database who have logged in(init_dtime) within 7 days of a specific date.

As it stands, I will have to run this query multiple times, for every “Day of Concern” that I wish to know about. Is there a better solution?

Answer 1

If you need to run this query for multiple dates, you would need some mean to hold more than one value. I suggest you use a NESTED TABLE object:

CREATE TYPE my_dates AS TABLE OF DATE;
/

SELECT d.column_value AS Date_Of_Concern, count(Player_Id) AS Retained
  FROM Player
  JOIN TABLE (my_dates(to_date('2012-sep-03', 'yyyy-mon-dd'),
                       to_date('2012-sep-04', 'yyyy-mon-dd'),
                       to_date('2012-sep-05', 'yyyy-mon-dd'))) d
          ON d.column_value - trunc(Init_Dtime) BETWEEN 0 AND 7
 GROUP BY d.column_value