Plz advise:
There is a table with the fields id, time.
Where time - user login time in Unix format (number of seconds since 01/01/1970). Each time a user logs in, a row is added to the table with his id and login time.
It is necessary to calculate for each user how many days he had logged in at least once.
If the ROUND values (time / (24 * 60 * 60), 0) are the same for two lines, we assume that the inputs were completed on the same day.