确定 Mysql 中的用户会话

Question

how can I determine the session times of these fictitious users? As an example, for user 1 I assume that between 08:24:08 and 15:08:20 he wasn't there, so I don't add that time interval, I add the other times.

So I look for a method to add up (in seconds or minutes) the intermediate times based on this table. Any ideas.

drop table sessions;
CREATE TABLE IF NOT EXISTS sessions (    
    id_user int(11),
    start_date datetime
);

insert into sessions values (1,'2020-02-21 08:24:07');
insert into sessions values (1,'2020-02-21 08:24:08');--> 1 seg (08:24:08 - 08:24:07)
insert into sessions values (1,'2020-02-21 15:08:20');
insert into sessions values (1,'2020-02-21 15:08:21');--> 1 seg (15:08:21 - 15:08:20)
insert into sessions values (1,'2020-02-21 15:08:22');--> 1 seg 
insert into sessions values (2,'2020-02-20 15:08:22');
insert into sessions values (2,'2020-02-20 15:15:22');--> 7 min (15:15:22 - 15:08:22)
insert into sessions values (3,'2020-02-20 15:08:22');
insert into sessions values (3,'2020-02-20 15:15:22');--> 7 min
insert into sessions values (3,'2020-02-20 15:20:22');--> 5 min

Answer 1

This shows you how you can accomplish that in mysql 5.x and higher

Please read the Text at the end for more information

CREATE TABLE IF NOT EXISTS `sessions` ( id_user int, `start_date` datetime ); insert into `sessions` values (1,'2020-02-21 08:24:07'); insert into `sessions` values (1,'2020-02-21 08:24:08'); insert into `sessions` values (1,'2020-02-21 15:08:20'); insert into `sessions` values (1,'2020-02-21 15:08:21'); insert into `sessions` values (1,'2020-02-21 15:08:22'); insert into `sessions` values (2,'2020-02-20 15:08:22'); insert into `sessions` values (2,'2020-02-20 15:15:22'); insert into `sessions` values (3,'2020-02-20 15:08:22'); insert into `sessions` values (3,'2020-02-20 15:15:22'); insert into `sessions` values (3,'2020-02-20 15:20:22');

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SELECT IF(@iduser = id_user,TIME_FORMAT(TIMEDIFF(`start_date`,@date), '%H:%i:%S'), NULL) Datediff ,@iduser := id_user iduser , @date := `start_date` `start_date` FROM (SELECT * FROM sessions ORDER by id_user ASC, start_date ASC) t ,(SELECT @iduser := 0) a,(SELECT @date := 0) b;

\nDatediff | iduser | start_date         \n:------- |  -----: |  :------------------ \nnull | 1 |  2020-02-21 08:24:07 \n00:00:01 |  1 |  2020-02-21 08:24:08 \n06:44:12 |  1 |  2020-02-21 15:08:20 \n00:00:01 |  1 |  2020-02-21 15:08:21 \n00:00:01 |  1 |  2020-02-21 15:08:22 \nnull | 2 |  2020-02-20 15:08:22 \n00:07:00 |  2 |  2020-02-20 15:15:22 \nnull | 3 |  2020-02-20 15:08:22 \n00:07:00 |  3 |  2020-02-20 15:15:22 \n00:05:00 |  3 |  2020-02-20 15:20:22 \n

db<>fiddle here

It uses TIMEDIFF to get the Difference between to rows.

And the uses TIME_FORMAT to get rid of the milliseconds.

The new Datediff column is at the start and must stay there so that the Algorithm can work . If you want to reorder it in mysql you need a new outer SELECT query.

The final problem with this algorithm is, that it simple makes time1 - time2, it doesn't care if a new day start, it would still make this for every id_user. It is possible to use a much more sophisticated ORDER BY clauses.