postgresql – 类型interval的输入语法无效

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"

如果我删除语句的-46 * interval’1 day’部分,它将按预期工作.

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;

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.