SQL查询中本地时间的18位时间戳

Question

I am using DB Browser for SQlite. My database also has date time stored in 18 digit time-stamp. Please help to convert it to Local Time within this query:

SELECT * FROM message WHERE handle_id=52 ORDER BY date DESC;   

I believe that this is a type of unix timestamp since the db is mac based. (Apple CoreD (nanosec) is the timestamp format, Thanks varro) Here are a couple of examples from the db:

561774860770410304 559334672583377600   

I came across another similar question (18 digit timestamp to Local Time), but the asker didn't need the answer in any particular language or platform.

Thanks, Alice

Answer 1

Without knowing beforehand the timestamp format, it's impossible to give a definitive answer, but I submit this script (which depends on the sqlite3 command line tool only) to help:

#!/bin/sh

printf "Enter timestamp: "
read number

sqlite3 <<EOS
.mode column
.width 12, 20

select 'Number:',     $number;
select 'Unix epoch:', datetime($number, 'unixepoch');
select 'Variant:',    datetime($number, 'unixepoch', '-70 years');
select 'Julian day:', datetime($number);
select 'Mac HFS+:',   datetime($number, 'unixepoch', '-66 years');
select 'Apple CoreD:';
select '  (seconds)', datetime($number, 'unixepoch', '+31 years');
select '  (nanosec)', datetime($number/1000000000, 'unixepoch', '+31 years');
select 'NET:',        datetime($number/10000000, 'unixepoch', '-1969 years');
EOS

If you run this script and enter your number 561774860770410304 , you will see the following:

% Enter timestamp: 561774860770410304
Number:       561774860770410304
Unix epoch:   -
Variant:      -
Julian day:   -
Mac HFS+:     -
Apple CoreD:
  (seconds)   -
  (nanosec)   2018-10-21 00:34:20
NET:          1781-03-12 09:14:37

I will guess that probably "2018-10-21 00:34:20" is your timestamp, and that accordingly "Apple CoreD (nanosec)"" is your timestamp format (see https://www.epochconverter.com/coredata ).

Answer 2

I think that your case might be like this: https://stackoverflow.com/a/36822906/10498828 .
The difference is that your date values are in nanoseconds, so you need first to divide with 1000000000:

select datetime(datecolumn/1000000000 + 978307200, 'unixepoch') from message 

For these values:

561774860770410304 559334672583377600

the above code gives:

2018-10-21 00:34:20 2018-09-22 18:44:32