Time - (Unix|POSIX|Epoch) time

> (Data|State) Management and Processing > (Data Type|Data Structure) > Time > Time - (Instant|Date) (representation|type)

1 - About

Unix time (also known as POSIX time or Epoch time) is a system for describing instants in time.

It is used widely in Unix-like and many other operating systems and file formats.

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3 - Definition

The number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970, not counting leap seconds.

Because it does not handle leap seconds, it is neither a linear representation of time nor a true representation of UTC.

4 - Command

4.1 - Bash / Linux

Unix time may be checked on most Unix systems by typing date +%s on the command line.

4.2 - Java

4.3 - Oracle

  • Example 1:
myDate = TO_DATE('19700101000000','YYYYMMDDHH24MISS') + NUMTODSINTERVAL(myUnixTimeStamp, 'SECOND')
  • Example 2:
SELECT TO_CHAR( FROM_TZ( CAST(DATE '1970-01-01' + (1/24/60/60/1000) * <COLUMN name> AS TIMESTAMP), 'America/New_York'), 'MM/DD/YYYY HH24:MI:SS') FROM <tablename>;
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5 - Documentation / Reference