most active time of day based on start and end time

Question

I\'m logging statistics of the gamers in my community. For both their online and in-game states I\'m registering when they \"begin\" and when they \"end\". In order to show the

Answer 1

This query is for oracle, but you can get idea from it:

SELECT
    H, M, 
    COUNT(BEGIN)
FROM
    -- temporary table that should return numbers from 0 to 1439
    -- each number represents minute of the day, for example 0 represents 0:00, 100 represents 1:40, etc.
    -- in oracle you can use CONNECT BY clause which is designated to do recursive queries
    (SELECT LEVEL - 1 DAYMIN, FLOOR((LEVEL - 1) / 60) H, MOD((LEVEL - 1), 60) M FROM dual CONNECT BY LEVEL <= 1440) T LEFT JOIN

    -- join stats to each row from T by converting discarding date and converting time to minute of a day
    STATS S ON 60 * TO_NUMBER(TO_CHAR(S.BEGIN, 'HH24')) + TO_NUMBER(TO_CHAR(S.BEGIN, 'MI')) <= T.DAYMIN AND
               60 * TO_NUMBER(TO_CHAR(S.END, 'HH24'))   + TO_NUMBER(TO_CHAR(S.END, 'MI'))   >  T.DAYMIN

GROUP BY H, M
HAVING COUNT(BEGIN) > 0
ORDER BY H, M

GROUP BY H, M
HAVING COUNT(BEGIN) > 0
ORDER BY H, M

Fiddle: http://sqlfiddle.com/#!4/e5e31/9

The idea is to have some temp table or view with one row for time point, and left join to it. In my example there is one row for every minute in day. In mysql you can use variables to create such view on-the-fly.

MySQL version:

SELECT
    FLOOR(T.DAYMIN / 60), -- hour
    MOD(T.DAYMIN, 60), -- minute
    -- T.DAYMIN, -- minute of the day
    COUNT(S.BEGIN) -- count not null stats
FROM
    -- temporary table that should return numbers from 0 to 1439
    -- each number represents minute of the day, for example 0 represents 0:00, 100 represents 1:40, etc.
    -- in mysql you must have some table which has at least 1440 rows; 
    -- I use (INFORMATION_SCHEMA.COLLATIONSxINFORMATION_SCHEMA.COLLATIONS) for that purpose - it should be
    -- in every database
    (
        SELECT 
            @counter := @counter + 1 AS DAYMIN
        FROM
            INFORMATION_SCHEMA.COLLATIONS A CROSS JOIN
            INFORMATION_SCHEMA.COLLATIONS B CROSS JOIN
            (SELECT @counter := -1) C
        LIMIT 1440
    ) T LEFT JOIN

    -- join stats to each row from T by converting discarding date and converting time to minute of a day
    STATS S ON (
        (60 * DATE_FORMAT(S.BEGIN, '%H')) + (1 * DATE_FORMAT(S.BEGIN, '%i')) <= T.DAYMIN AND
        (60 * DATE_FORMAT(S.END, '%H'))   + (1 * DATE_FORMAT(S.END, '%i'))   >  T.DAYMIN
    )

GROUP BY T.DAYMIN
HAVING COUNT(S.BEGIN) > 0 -- filter empty counters
ORDER BY T.DAYMIN

Fiddle: http://sqlfiddle.com/#!2/de01c/1