time - 将 秒添加到 PostgreSQL 中的

Question

我有一个包含以下列的项目表:

• start_time 列(不带时区的时间戳)
• expiration_time_seconds 列(整数)

例如，一些值是:

SELECT start_time, expiration_time_seconds 
   FROM whatever 
       ORDER BY start_time;

         start_time         | expiration_time_seconds
----------------------------+-------------------------
 2014-08-05 08:23:32.428452 |                  172800
 2014-08-10 09:49:51.082456 |                    3600
 2014-08-13 13:03:56.980073 |                    3600
 2014-08-21 06:31:38.596451 |                    3600
 ...

如何将过期时间(以秒为单位)添加到 start_time 中？

我尝试为 interval 命令格式化时间间隔字符串，但失败了:

blah=> SELECT interval concat(to_char(3600, '9999'), ' seconds');
ERROR:  syntax error at or near "("
LINE 1: SELECT interval concat(to_char(3600, '9999'), ' seconds');

Answer 1

trick是创建一个固定的时间间隔，并将其与列中的秒数相乘:

SELECT start_time, 
       expiration_time_seconds, 
       start_time + expiration_time_seconds * interval '1 second'
FROM whatever 
ORDER BY start_time;

        start_time          | expiration_time_seconds |          end_time
----------------------------|-------------------------|----------------------------
 2014-08-05 08:23:32.428452 |                  172800 | 2014-08-07 08:23:32.428452
 2014-08-10 09:49:51.082456 |                    3600 | 2014-08-10 10:49:51.082456
 2014-08-13 13:03:56.980073 |                    3600 | 2014-08-13 14:03:56.980073
 2014-08-21 06:31:38.596451 |                    3600 | 2014-08-21 07:31:38.596451