PostgreSQL存储过程数据参数

我有以下存储过程,它返回0结果,但如果单独运行查询,则会产生大量结果.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结果

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

返回100结果

解决方法

您将baselineDate参数声明为日期：

CREATE OR REPLACE FUNCTION countStatistics(baselineDate Date)

但使用它作为时间戳：

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

您正在获得隐式转换,因此countStatistics(‘2015-01-01 01:00:00’)将实际执行此sql：

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

并且,在将日期隐式地转换回时间戳之后,它实际上将是这样的：

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

尝试更改函数声明以使用时间戳：

CREATE OR REPLACE FUNCTION countStatistics(baselineDate timestamp)