类型区间的输入语法无效

Question

我遇到一个问题,我无法在postgresql中添加间隔到日期.在MySql中我会这样做:

date_add('2015-02-02', interval -46 day)

与postgresql中的相应语句是:

'2015-02-02' + -46 * interval '1 day'

但是,当我这样做时,我得到一个错误:

[Err] ERROR:  invalid input syntax for type interval: "2015-02-02"

如果我删除该+ -46 * interval '1 day'语句的部分,它按预期工作.

简化查询:

SELECT
    cd.date_sort_prequeue_start AS date,
    SUM(CASE WHEN cd.call_conclusion='Answered' THEN 1 ELSE 0 END) AS calls_answered
FROM 
    data_warehouse.call_detail AS cd
    INNER JOIN data_warehouse.users_history AS uh ON cd.users_history_id=uh.id
WHERE 
    cd.date_sort_prequeue_start>= '2015-02-02' + (-46 * INTERVAL '1 day') 
    AND cd.date_sort_prequeue_start<'2015-02-02' 
    AND cd.call_type='I' AND uh.team='TeamOne'
GROUP BY 
    cd.date_sort_prequeue_start
ORDER BY 
    cd.date_sort_prequeue_start;

Answer 1

如果将字符串转换为日期,则可以解决问题:

'2015-02-02'::date + -46 * interval '1 day'

字符串本身是不明确的,因为有几种不同的类型来表示时间.

Answer 2

一个更简单的方法是：

date '2015-02-02' - interval '46 days'