Hello,
I see two problems here:
1. The times in your database are not “+6” hours, they are in UTC and your timezone is “-6” hours.
If all the database entries are in correct UTC time, rather than local time, then you should leave them as they are (i.e. not modify the original data).
Then, it is easy to construct a query that converts this data to any timezone and choose and export a particular day according to your local time.
2. This is not how you would construct such an SQL query. You’d have to use MySQL’s date/time functions. I would start by creating a temporary table or view or subquery with the offset data ( see CONVERT_TZ() ), then select from that data.
with regards