PostgreSQL 存储过程数据参数

Question

我有一个存储过程，它返回0个结果，但是如果单独运行查询，则会返回很多结果。我错过了什么。

CREATE OR REPLACE FUNCTION countStatistics(baselineDate Date) RETURNS int AS $$
DECLARE
    qty int;
BEGIN
    SELECT COUNT(*) INTO qty FROM statistics WHERE time_stamp = baselineDate;
    RETURN qty;
END;
$$ LANGUAGE plpgsql;

--Execute the function
SELECT countStatistics('2015-01-01 01:00:00') as qty;

返回0个结果

SELECT COUNT(*) FROM statistics WHERE time_stamp = '2015-01-01 01:00:00';

返回100+结果

- user373201

Answer 1

您将baselineDate参数声明为date类型：

CREATE OR REPLACE FUNCTION countStatistics(baselineDate Date)

但是将其作为时间戳使用：

SELECT COUNT(*) INTO qty FROM statistics WHERE time_stamp = baselineDate;

您正在进行隐式转换，因此countStatistics('2015-01-01 01:00:00')将实际执行以下SQL：

SELECT COUNT(*) INTO qty FROM statistics WHERE time_stamp = '2015-01-01';

在将date隐式转换回timestamp后，它实际上将变成这样：

SELECT COUNT(*) INTO qty FROM statistics WHERE time_stamp = '2015-01-01 00:00:00';

尝试将函数声明更改为使用 时间戳:

CREATE OR REPLACE FUNCTION countStatistics(baselineDate timestamp)

- mu is too short