mysql 不同的服务器，相同的内容，不同的计数

Question

我有 2 个服务器，live 和 beta，并且在 live 和 beta 之间有 2 个相同的数据库，但是 count() 返回不同的数字

直播:

mysql> SELECT COUNT(*) FROM `tbl_application_user` WHERE created >= '2014-06-01 00:00:01' and created < '2014-07-01 23:59:59';
+----------+
| COUNT(*) |
+----------+
|     3432 |
+----------+
1 row in set (0.02 sec)

测试版(ubuntu、mysql):

mysql> SELECT COUNT(*) FROM `tbl_application_user` WHERE created >= '2014-06-01 00:00:01' and created < '2014-07-01 23:59:59';
+----------+
| COUNT(*) |
+----------+
|     3444 |
+----------+
1 row in set (0.00 sec)

当我在我的笔记本电脑(Windows 8.1，mysql)上尝试本地 mysql 时，它返回与实时相同的数字。

mysql> SELECT COUNT(*) FROM `tbl_application_user` WHERE created >= '2014-06-01
00:00:01' and created < '2014-07-01 23:59:59';
+----------+
| COUNT(*) |
+----------+
|     3432 |
+----------+
1 row in set (0.03 sec)
mysql>

是什么导致 BETA 服务器返回不同的数字？

谢谢，

Answer 1

BETA 服务器上的时区可能与其他机器上的时区不同。虽然时间和日期存储为 UTC，但当按字面意义使用时，它们将在连接的时区中解释，如查询的 WHERE 部分。

供您引用:11.3.1 The DATE, DATETIME, and TIMESTAMP Types

MySQL converts TIMESTAMP values from the current time zone to UTC for storage, and back from UTC to the current time zone for retrieval. (This does not occur for other types such as DATETIME.) By default, the current time zone for each connection is the server's time. The time zone can be set on a per-connection basis. As long as the time zone setting remains constant, you get back the same value you store. If you store a TIMESTAMP value, and then change the time zone and retrieve the value, the retrieved value is different from the value you stored. This occurs because the same time zone was not used for conversion in both directions. The current time zone is available as the value of the time_zone system variable. For more information, see Section 10.6, “MySQL Server Time Zone Support”.