Date and Time Functions If you use  UNIX_TIMESTAMP()  and  FROM_UNIXTIME()  to convert between values in a non-UTC time zone and Unix timestamp values, the conversion is lossy because the mapping is not one-to-one in both directions. For example, due to conventions for local time zone changes such as Daylight Saving Time (DST), it is possible for  UNIX_TIMESTAMP()  to map two values that are distinct in a non-UTC time zone to the same Unix timestamp value.  FROM_UNIXTIME()  maps that value back to only one of the original values. Here is an example, using values that are distinct in the  MET  time zone: To use named time zones such as  ’MET’  or  ’Europe/Amsterdam’ , the time zone tables must be properly set up. For instructions, see Section 5.1.15, “MySQL Server Time Zone Support” . If you want to subtract  UNIX_TIMESTAMP()  columns, you might want to cast them to signed integers. See Section 12.11, “Cast Functions and Operators” . Returns the current UTC date as a value in  ’ YYYY-MM-DD ’  or  YYYYMMDD  format, depending on whether the function is used in string or numeric context. mysql>  SELECT UTC_DATE(), UTC_DATE() + 0; -> ’2003-08-14’, 20030814 Returns the current UTC time as a value in  ’hh:mm:ss’  or  hhmmss  format, depending on whether the function is used in string or numeric context. If the  fsp  argument is given to specify a fractional seconds precision from 0 to 6, the return value includes a fractional seconds part of that many digits. mysql>  SELECT UTC_TIME(), UTC_TIME() + 0; -> ’18:07:53’, 180753.000000 2168 • UTC_TIME ,  UTC_TIME([ fsp ]) • UTC_DATE ,  UTC_DATE() -> 1447431666 mysql>  SELECT UNIX_TIMESTAMP(’2015-11-13 10:20:19’); -> 1447431619 mysql>  SELECT UNIX_TIMESTAMP(’2015-11-13 10:20:19.012’); -> 1447431619.012 mysql>  SET time_zone = ’MET’; mysql>  SELECT UNIX_TIMESTAMP(’2005-03-27 03:00:00’); +---------------------------------------+ | UNIX_TIMESTAMP(’2005-03-27 03:00:00’) | +---------------------------------------+ | 1111885200 | +---------------------------------------+ mysql>  SELECT UNIX_TIMESTAMP(’2005-03-27 02:00:00’); +---------------------------------------+ | UNIX_TIMESTAMP(’2005-03-27 02:00:00’) | +---------------------------------------+ | 1111885200 | +---------------------------------------+ mysql>  SELECT FROM_UNIXTIME(1111885200); +---------------------------+ | FROM_UNIXTIME(1111885200) | +---------------------------+ | 2005-03-27 03:00:00 | +---------------------------+ Note