问题
When looking at the History.db from Safari, there's a table named history_visits which has a column named visit_time, which is a REAL value. It has values such as 470799793.096987. What format is that in? I'd like to see it in a format such as 12/08/2015 05:12:05.
回答1:
It's the number in seconds since 00:00:00 UTC on 1 January 2001. It must be coming from an NSDate.
NSDate objects encapsulate a single point in time, independent of any particular calendrical system or time zone. Date objects are immutable, representing an invariant time interval relative to an absolute reference date (00:00:00 UTC on 1 January 2001).
— NSDate Class Reference
To get a decent human value out of it, you must add 978307200 (the epoch for 2001-01-01 00:00:00).
This query should give you what you want:
.headers on
select datetime(v.visit_time + 978307200, 'unixepoch', 'localtime') as date, v.visit_time + 978307200 as epoch, v.visit_time, i.domain_expansion, i.url
from history_items i left join history_visits v on i.id = v.history_item
order by i.id desc
limit 100;
Example output:
date|epoch|visit_time|domain_expansion|url
2015-12-31 11:51:27|1451562687.28465|473255487.284646|duckduckgo|https://duckduckgo.com/?q=current+timestamp+2015-12-31+11:51&t=osx
PS: Just for future reference, the Safari db file is located at ~/Library/Safari/History.db
回答2:
To convert the visit_time value in the history.db in an excel spread sheet, open the history.db file in a tool such as DB browser for SQLLite (Windows) and export the history_visits values to a CSV file.
Open the CSV file and create a column where you will populate your values in human readable time adjusted to your time zone, and use the following formula convert your NSDate:
=((((C2+978307200)/60)/60)/24)+DATE(1970,1,1)+(-5/24)
In the above formula, the time value is in cell C2, and my time zone GMT-5. To adjust to your own time zone adjust the statement in the last set of parenthesis. Presently I have (-5/24) to represent GMT-5.
When I first approached this conversion, I mistakenly assumed the time in the history.db to be epoch time, which starts at 1/1/1970, and did not understand why there was such a skew in time. Adding the required conversion factor +978307200 solved the problem.
来源：https://stackoverflow.com/questions/34167003/what-format-is-the-safari-history-db-history-visits-visit-time-in