Count incremental user day by day

[Samu_512]

Hi all!

i have a table with daily user log in, i need to count day by day the distinct user.

Example:

day	user_id
01-gen	1
01-gen	2
02-gen	1
02-gen	3
03-gen	4
03-gen	3
04-gen	2
04-gen	3

The results i need is:

day	user_id
01-gen	2
02-gen	3
03-gen	4
04-gen	4

where at 1st i have 2 user logged in, at 2nd 3 user.... and at 4th of the month i don't have new user so stay at 4 user logged.

To complicate i have to do this for two year, whit a view of month.

how can i do?