서울              UTC +9  2018-07-16  14:05
하노이            UTF +7              19:05
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UTC >> 나라
CONVERT_TZ(a.mb_datetime, '+00:00','".G5_TIMEZONETZ."') as mb_datetime,
나라 >> UTC
$fc_datetime  = _get_utcavn_zone(G5_TIMEZONE, $fc_datetime, 'UTC', 'D');  // 2018-05-16 15:58:00

$stx_utc = _get_utcavn_zone(G5_TIMEZONE, $stx.' 00:00:00', 'UTC', 'R');  // 2018-05-16
$etx_utc = _get_utcavn_zone(G5_TIMEZONE, $etx.' 23:59:59', 'UTC', 'R');  // 2018-05-16

UTC_TIMESTAMP()


G5_TIMEZONE  : 현재 날짜 (Asia/Seoul)
G5_TIMEZONETZ : '+07:00'

#기록할때
#나라 >> UTC
_get_utcavn_zone(G5_TIMEZONE, '2018-05-16 00:00:00', 'UTC', 'T');  // 타임값으로 리턴
_get_utcavn_zone(G5_TIMEZONE, '2018-05-16 00:00:00', 'UTC', 'D');  // 2018-05-16 15:58:00
_get_utcavn_zone(G5_TIMEZONE, '2018-05-16 00:00:00', 'UTC', 'R');  // 2018-05-16