unix_timestamp 函数可以将日期时间转换为 unix 时间戳。
| SQL | 执行结果 |
|---|---|
| select unix_timestamp('2019-01-05 22:29:36'); | 1546698576 |
| select unix_timestamp('2019-01-05 00:00:00'); | 1546617600 |
| select unix_timestamp('2019-01-05'); | 1546617600 |
| select unix_timestamp('2019/01/05'); | 1546617600 |
| select unix_timestamp(now()); | 当前的时间戳, 如 1586576346 |
| select unix_timestamp(); | 当前的时间戳, 如 1586576346 |
限制：unix_timestamp 能处理的时间上限是 int 最大值 2147483647 对应的时间 2038-01-19 11:14:07。超出后，会处理成 0 。
mysql> select unix_timestamp('2038-01-19 11:14:07');
+---------------------------------------+
| unix_timestamp('2038-01-19 11:14:07') |
+---------------------------------------+
| 2147483647 |
+---------------------------------------+
mysql> select unix_timestamp('2038-01-19 11:14:08');
+---------------------------------------+
| unix_timestamp('2038-01-19 11:14:08') |
+---------------------------------------+
| 0 |
+---------------------------------------+