要得到天数，最简单的方法是:

SELECT EXTRACT(DAY FROM NOW() - '2014-08-02 08:10:56');

据我所知，它将返回相同的:

SELECT (EXTRACT(epoch FROM (SELECT (NOW() - '2014-08-02 08:10:56')))/86400)::int;

如果你转换表字段:

定义字段，使其包含秒: 创建表如果不存在测试( .．. 字段INTERVAL秒(0) ）; 提取值。记住，如果转换为int，你可能会在间隔变大时得到一个不愉快的惊喜: EXTRACT(EPOCH FROM field)::int

可能最简单的方法是:

SELECT EXTRACT(epoch FROM my_interval)/3600

如果你想要整数，即天数:

SELECT (EXTRACT(epoch FROM (SELECT (NOW() - '2014-08-02 08:10:56')))/86400)::int

         select date 'now()' - date '1955-12-15';

下面是一个简单的查询，计算总天数。

我正在使用PostgreSQL 11，我创建了一个函数来获得2个不同时间戳之间的时间

create function analysis.calcHours(datetime1 timestamp, datetime2 timestamp)
    returns integer
    language plpgsql as $$
    declare
        diff interval;
    begin
        diff = datetime2 - datetime1;
        return (abs(extract(days from diff))*24 + abs(extract(hours from diff)))::integer;
    end; $$;