Re: SQL to return maximum number of users logged in to a single project (or all projects)

I'm not an SQL expert, but I faced the same problem and came up with the following solution.

What I was interested in was the peak number of licences used for one day (you'll be able to tweak the following queries to extend the period to several days and/or limit to one or several projects).

The SESSIONS_HISTORY table records the start and end times for each session. To know the number of concurrent sessions  opened a a given point of time, we can compute a running total on a table with the following columns :

Row Number, time, +1 if it is a start time or -1 if it is an end time ; of course we would order that table by time.

One of the problems is that the SESSIONS_HISTORY table includes all sessions, even those that do not use any licence, e.g. OTAClient.

This is why we need to first get all session id's from the SESSION_LICENCE_HISTORY table. But, as a regular (Client UI) session can use more than one licence, we need to select only distinct session id's. This is the prupose of the L table in the following queries.

This gives the following query in Oracle :

WITH L AS (SELECT DISTINCT SLH_SESSION_ID FROM SESSION_LICENSE_HISTORY)
    ,O AS (select rownum i, t ,c from(SELECT  t, c FROM
                 (SELECT START_TIME as t, 1 as c FROM SESSIONS_HISTORY WHERE TO_CHAR(START_TIME, 'dd/mm/yyyy') = '23/10/2012' AND SESSION_ID in (SELECT * FROM L)
            UNION ALL SELECT END_TIME as t, -1 as c FROM SESSIONS_HISTORY WHERE TO_CHAR(START_TIME, 'dd/mm/yyyy') = '23/10/2012' AND SESSION_ID in (SELECT * FROM L))
           ORDER BY t))
SELECT MAX (total) FROM
(SELECT a.i, a.t, a.c, (SELECT SUM(b.c) FROM O b WHERE b.i <= a.i) total
FROM O a) runningtotal

And in SQL Server :

WITH L AS (SELECT DISTINCT SLH_SESSION_ID FROM td.SESSION_LICENSE_HISTORY)
    ,O AS (SELECT ROW_NUMBER()OVER (ORDER BY t ASC) i, t ,c FROM
               (SELECT t, c FROM
                   (SELECT START_TIME as t, 1 as c FROM td.SESSIONS_HISTORY WHERE CONVERT(VARCHAR(10), START_TIME, 103) = '11/06/2013' AND SESSION_ID in (SELECT * FROM L)
                    UNION ALL SELECT END_TIME as t, -1 as c FROM td.SESSIONS_HISTORY WHERE CONVERT(VARCHAR(10), START_TIME, 103) = '11/06/2013' AND SESSION_ID in (SELECT * FROM L)
                   ) allsessions
               ) allordered
           )
SELECT MAX (total) FROM
(SELECT a.i, a.t, a.c, (SELECT SUM(b.c) FROM O b WHERE b.i <= a.i) total
FROM O a) runningtotal

To query more than one day, modify the WHERE clause of the allsessions table. Ditto to query on one or several projects only.

These queries do NOT give the same numbers as the Site Analysis. One of the reasons is that sessions can last more than one day, which means that you may have a non-zero starting point for the running total.

To use these queries, you'll need an external tool, such as SQL Developer or SQL Server Management Studio or TOAD or ...