sql - 如何在更新中将 bigint 转换为带时区的时间戳

Question

有没有办法在 Postgres 中将 BIGINT 转换为 TIMESTAMP 或 TIMESTAMP WITH TIME ZONE？我需要将数据从 BIGINT 列复制到 TIMESTAMP 列。

这是我尝试过的:

update table
set date__timestamp = date__bigint::timestamp 
where foo = 1;

ERROR: cannot cast type bigint to timestamp without time zone

我将时间戳列更改为带有时区的列并尝试了这个:

update table
set date__timestamp = date__bigint::timestamp with time zone at time zone 'PST' 
where foo = 1;

ERROR: cannot cast type bigint to timestamp with time zone

update table
set date__timstamp = TO_CHAR(TO_TIMESTAMP(date__bi / 1000), 'DD/MM/YYYY HH24:MI:SS')
where foo = 1;

ERROR: column "date__timestamp" is of type timestamp without time zone but expression is of type text Hint: You will need to rewrite or cast the expression.

数据看起来像这样。

date_bigint: 20181102
date_timestamp: 2018-11-02 17:00:00.000000

我需要将默认值传递给转换吗？

Answer 1

您可以将其转换为文本并使用 TO_TIMESTAMP 并转换为 timestamp at time zone

SELECT 
to_timestamp ( '20181102'::bigint::text,'YYYYMMDD')::timestamp at time zone 'UTC' 
at time zone 'PST' ;

update t
   set date__timestamp = TO_TIMESTAMP(date_bigint::text,'YYYYMMDD')::timestamp 
   at time zone 'UTC' at time zone 'PST'
where foo = 1;

Demo