Getting “unixtime” in Java
long unixTime = System.currentTimeMillis() / 1000L;
GUI Converter : http://www.epochconverter.com/
What is epoch time?
The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970 (midnight UTC/GMT), not counting leap seconds (in ISO 8601: 1970-01-01T00:00:00Z). Literally speaking the epoch is Unix time 0 (midnight 1/1/1970), but 'epoch' is often used as a synonym for 'Unix time'. Many Unix systems store epoch dates as a signed 32-bit integer, which might cause problems on January 19, 2038 (known as the Year 2038 problem or Y2038).
Human readable time
Seconds
1 minute
60 seconds
1 hour
3600 seconds
1 day
86400 seconds
1 week
604800 seconds
1 month (30.44 days)
2629743 seconds
1 year (365.24 days)
31556926 seconds
ตามที่ผมเข้าใจ คือ unix time มีการนับเวลาเป็นวินาที และ นับวินาทีแรก เมื่อปีJanuary 1, 1970 (midnight UTC/GMT),
ฉะนั้น เวลาเราอ่าน เราก็จะได้เวลา ตาม Human readable time นั่นเอง
ที่ผมชอบคือเว็บนี้มีวิธี อ่านเขียน unix time ได้ในหลายๆ ภาษา ดังนี้
แต่ที่ผมต้องการคือ Mysql อ่าน เขียน unix time
ทำให้ เป็น unix time :: UNIX_TIMESTAMP( now() )
อ่าน จาก unix time :: FROM_UNIXTIME( UNIX_TIMESTAMP( now() ))
How to get the current epoch time in ...
Perl
time
PHP
time()
Ruby
Time.now (or Time.new). To display the epoch: Time.now.to_i
Python
import time first, then time.time()
Java
long epoch = System.currentTimeMillis()/1000;
Microsoft .NET C#
epoch = (DateTime.Now.ToUniversalTime().Ticks - 621355968000000000) / 10000000;
VBScript/ASP
DateDiff("s", "01/01/1970 00:00:00", Now())
Erlang
calendar:datetime_to_gregorian_seconds(calendar:now_to_universal_time( now()))-719528*24*3600.
MySQL
SELECT unix_timestamp(now()) More info (+ negative epochs)
PostgreSQL
SELECT extract(epoch FROM now());
Oracle PL/SQL
SELECT (SYSDATE - TO_DATE('01/01/1970 00:00:00', 'MM-DD-YYYY HH24:MI:SS')) *
24 * 60 * 60 FROM DUAL
SQL Server
SELECT DATEDIFF(s, '1970-01-01 00:00:00', GETUTCDATE())
JavaScript
Math.round(new Date().getTime()/1000.0) getTime() returns time in milliseconds.
Unix/Linux Shell
date +%s
PowerShell
Get-Date -UFormat "%s" Produces: 1279152364.63599
Other OS's
Command line: perl -e "print time" (If Perl is installed on your system)
Convert from human readable date to epoch
Perl
Use these Perl Epoch routines
PHP
mktime(hour, minute, second, month, day, year)
Ruby
Time.local(year, month, day, hour, minute, second, usec ) (or Time.gm for GMT/UTC input). To display add .to_i
Python
import time first, then int(time.mktime(time.strptime('2000-01-01 12:34:00', '%Y-%m-%d %H:%M:%S'))) - time.timezone
Java
long epoch = new java.text.SimpleDateFormat ("MM/dd/yyyy HH:mm:ss").parse("01/01/1970 01:00:00").getTime();
VBScript/ASP
DateDiff("s", "01/01/1970 00:00:00", time field)
MySQL
SELECT unix_timestamp(time) Time format: YYYY-MM-DD HH:MM:SS or YYMMDD or YYYYMMDD
More on using Epoch timestamps with MySQL
PostgreSQL
SELECT extract(epoch FROM date('2000-01-01 12:34'));
With timestamp: SELECT EXTRACT(EPOCH FROM TIMESTAMP WITH TIME ZONE '2001-02-16 20:38:40-08');
With interval: SELECT EXTRACT(EPOCH FROM INTERVAL '5 days 3 hours');
SQL Server
SELECT DATEDIFF(s, '1970-01-01 00:00:00', time field)
JavaScript
use the JavaScript Date object
Unix/Linux Shell
date +%s -d"Jan 1, 1980 00:00:01" Replace '-d' with '-ud' to input in GMT/UTC time.
Convert from epoch to human readable date
Perl
Use these Perl Epoch routines
PHP
date(output format, epoch); Output format example: 'r' = RFC 2822 date
Ruby
Time.at(epoch)
Python
import time first, then time.strftime("%a, %d %b %Y %H:%M:%S +0000", time.localtime(epoch)) Replace time.localtime with time.gmtime for GMT time.
Java
String date = new java.text.SimpleDateFormat("MM/dd/yyyy HH:mm:ss").format(new java.util.Date (epoch*1000));
VBScript/ASP
DateAdd("s", epoch, "01/01/1970 00:00:00")
MySQL
from_unixtime(epoch, optional output format) The default output format is YYY-MM-DD HH:MM:SS more ...
PostgreSQL
PostgreSQL version 8.1 and higher: SELECT to_timestamp(epoch); Older versions: SELECT TIMESTAMP WITH TIME ZONE 'epoch' + epoch * INTERVAL '1 second';
SQL Server
DATEADD(s, epoch, '1970-01-01 00:00:00')
Microsoft Excel
=(A1 / 86400) + 25569 Format the result cell for date/time, the result will be in GMT time (A1 is the cell with the epoch number). For other timezones: =((A1 +/- timezone adjustment) / 86400) + 25569.
Crystal Reports
DateAdd("s", {EpochTimeStampField}-14400, #1/1/1970 00:00:00#) -14400 used for Eastern Standard Time. See Timezones.
JavaScript
use the JavaScript Date object
Unix/Linux Shell
date -d @1190000000 Replace 1190000000 with your epoch, needs recent version of 'date'. Replace '-d' with '-ud' for GMT/UTC time.
PowerShell
Function get-epochDate ($epochDate) { [timezone]::CurrentTimeZone.ToLocalTime(([datetime]'1/1/1970').AddSeconds($epochDate)) }, then use: get-epochDate 1279152364. Works for Windows PowerShell v1 and v2
Other OS's
Command line: perl -e "print scalar(localtime(epoch))" (If Perl is installed) Replace 'localtime' with 'gmtime' for GMT/UTC time.
Ref : http://goo.gl/YpifR
