从mysql生成谷歌图表api的数据？

I am trying to integrate a chart that displays the number of users registrations per days for the last 30 days. I have a user table that stores the timestamp of when the user joined. Is there a way for me to group by that timestamp while still checking if it's within that same day. I am slightly lost on how exactly I can generate this type of data, and is it possible based on my table structure?

Thank you

You mean GROUP BY DATE(timestamp_column) ?

But I think it's faster to have an additional separate Date column as well and GROUP on that.

For the last 30 days.

SELECT ....
FROM ....
WHERE `timestamp_column` 
       BETWEEN DATE_SUB(CURDATE(), INTERVAL 30 DAY) AND CURDATE()
GROUP BY DATE(`timestamp_column`)