如何从 UTC 时间获取 MySQL 中的 Unix 时间戳？

Question

如果我使用unix_timestamp(some_date)，它会在内部将some_date 转换为UTC，而some_date 已经是UTC。有没有办法获取当前的 Unix 时间戳？

编辑：我需要 UTC 时间的 Unix 时间戳。

Answer 1

您应该能够首先使用CONVERT_TZ 将其从UTC 转换为本地时区：

UNIX_TIMESTAMP(CONVERT_TZ(some_date, '+00:00', @@global.time_zone))

另见：10.6. MySQL Server Time Zone Support

Answer 2

您可以从 UTC 日期时间值获取 MySQL 中的 UNIX 时间戳，如下所示：

SELECT 
UNIX_TIMESTAMP(CONVERT_TZ("some_date", '+00:00', @@session.time_zone)) 
FROM `table_name`

我在这里做了一个备忘单：Should MySQL have its timezone set to UTC?

Answer 3

这对我来说很好用：

UNIX_TIMESTAMP(CONVERT_TZ("some_date", '+00:00', 'SYSTEM'))

Answer 4

还有其他几种方法：

SELECT UNIX_TIMESTAMP(myDate)+UNIX_TIMESTAMP(NOW())-UNIX_TIMESTAMP(UTC_TIMESTAMP()) 
FROM myTable

 

SELECT UNIX_TIMESTAMP(myDate)-TIMESTAMPDIFF(SECOND, NOW(), UTC_TIMESTAMP()) 
FROM myTable

Answer 5

因为两个原因：

1. MySQL 的内置函数UNIX_TIMESTAMP 和FROM_UNIXTIME 采用存储在@@global.time_zone 中的时区，我通常不希望/能够更改，并且
2. DST 更改时的内置行为（如果全球时区使用 DST）在某些用例中会导致信息丢失，

我首选的解决方案是编写我自己的函数来转换为 Unix 时间戳并返回：

DELIMITER $$
CREATE FUNCTION UnixTimestamp(utcstamp DATETIME) RETURNS BIGINT UNSIGNED DETERMINISTIC
BEGIN
 DECLARE y INT UNSIGNED;
 SET y = YEAR(utcstamp);
 RETURN (y - 1970)          * 365 * 24 * 60 * 60 -- total seconds in full years since 1970
      + FLOOR((y - 1969) / 4)     * 24 * 60 * 60 -- add to that total seconds in extra days for each leap year
      - FLOOR((y - 1901) / 100)   * 24 * 60 * 60 -- subtract seconds for each day in a year that is divisible by 100 because those are not leap years
      + FLOOR((y - 1601) / 400)   * 24 * 60 * 60 -- but add back each day in a leap year that is divisible by 400 because those are leap years
      + (DAYOFYEAR(utcstamp) - 1) * 24 * 60 * 60 -- total seconds in full days since beginning of year
      + HOUR(utcstamp)                 * 60 * 60 -- total seconds for each full hour passed since beginning of day
      + MINUTE(utcstamp)                    * 60 -- total seconds for each full minute since last full hour
      + SECOND(utcstamp);                        -- seconds since last full minute
END$$
DELIMITER ;

DELIMITER $$
CREATE FUNCTION FromUnixtime(utcstamp BIGINT UNSIGNED) RETURNS DATETIME DETERMINISTIC
BEGIN
 DECLARE s INT UNSIGNED;
 DECLARE d INT UNSIGNED;
 DECLARE y INT UNSIGNED;
 IF utcstamp = 0 THEN RETURN '1970-01-01 00:00:00';
 END IF;
 SET s = utcstamp % (24 * 60 * 60);
 SET d = FLOOR(utcstamp / (24 * 60 * 60)) + 365 * 370 + 90;         -- days since 1600-01-01, last full leap year period
 SET y = 1600 + FLOOR(d / (400 * 365 + 97)) * 400;                  -- year is now 1600 + 400 * n, where n >= 0
 SET d = d - (400 * 365 + 97) * FLOOR(d / (400 * 365 + 97));        -- days since 1600 + 400 * n, less than 400 years
 IF d > 0 THEN
  SET y = y + FLOOR((d - 1) / (100 * 365 + 24)) * 100;              -- year is now 1600 + 400 * n + 100 * m, where 4 > m >= 0
  SET d = d - (100 * 365 + 24) * FLOOR((d - 1) / (100 * 365 + 24)); -- days since 1600 + 400 * n + 100 * m, less than 100 years
  SET y = y + FLOOR(d / (4 * 365 + 1)) * 4;                         -- year is now 1600 + 400 * n + 100 * m + 4 * l, where 25 > l >= 0
  SET d = d - (4 * 365 + 1) * FLOOR(d / (4 * 365 + 1));             -- days since 1600 + 400 * n + 100 * m + 4 * l, less than 4 years
  IF d > 0 THEN
   SET y = y + FLOOR(d / 365);                                      -- year is now 1600 + 400 * n + 100 * m + 4 * l + k, where 4 > k >= 0
   SET d = d - 365 * FLOOR(d / 365);                                -- days since 1600 + 400 * n + 100 * m + 4 * l + k, less than a year
   IF (y % 400 = 0 OR (y % 4 = 0 AND y % 100 <> 0)) THEN            -- if it's a leap year
    IF d > 0 THEN                                                   -- and if it's not day 0
     SET d = d + 1;                                                 -- add a day we dropped in a previous step
    ELSEIF d = 0 THEN                                               -- otherwise if it's day 0
     SET d = 365;                                                   -- then it's actually New Year's Eve
     SET y = y - 1;                                                 -- on the year before
    END IF;
   END IF;
  ELSE SET d = d + 1;
  END IF;
 ELSE SET d = d + 1;
 END IF;
 RETURN CONCAT(MAKEDATE(y, d), ' ', LPAD(FLOOR(s / 3600), 2, 0), ':', LPAD(FLOOR((s - FLOOR(s / 3600) * 3600) / 60), 2, 0), ':', LPAD(s % 60, 2, 0));
END$$
DELIMITER ;

你可以通过执行来检查这些函数：

SELECT UTC_TIMESTAMP() AS CurrentTime, FromUnixtime(UnixTimestamp(UTC_TIMESTAMP())) AS Result;

CurrentTime 和 Result 应该相同。