从UTC中的日期和时间获取时间戳

Question

I have table that have date and time with timezone.

date_time_table
+------------+--------------+
|   date_t   |   time_tz    |
+------------+--------------+
| 2016-05-13 | 23:00:00 -02 |
| 2016-05-14 | 13:00:00 +06 |
+------------+--------------+

After that I run SQL for query 'UTC' time

SELECT timetz AT TIME ZONE 'UTC' FROM date_time_tz

The result is:

+--------------+
|   time_tz    |
+--------------+
| 01:00:00 +00 |
| 07:00:00 +00 |
+--------------+

Can I write SQL combined date_t with time_tz for calculate with date too?

The result that I expect is:

+------------+------------+
|      date_time_tz       |
+------------+------------+
| 2016-05-14 01:00:00 +00 |
| 2016-05-14 07:00:00 +00 |
+------------+------------+

I try with :

SELECT concat(date_t , ' ' ,time_tz) AT TIME ZONE 'UTC' FROM date_time_table

But it does not work.

Answer 1

If the columns are of date and time types:

select (current_date + current_time) at time zone 'UTC';
          timezone          
----------------------------
 2016-07-12 12:06:00.239396

If those columns are text:

select ('2016-01-01'::date + '23:00:00 -02'::timetz) at time zone 'UTC';
      timezone       
---------------------
 2016-01-02 01:00:00

Answer 2

SELECT concat(date_t , ' ' ,time_tz)::timestamp AT TIME ZONE 'UTC' FROM date_time_table

尝试像这样铸造