Question

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

Answer 1

您将baselineDate参数声明为date：

CREATE OR REPLACE FUNCTION countStatistics(baselineDate Date)

但将其用作timestamp：

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')将实际执行此SQL：

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

并且，date被隐式转回timestamp之后，实际上会是这样：

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

尝试更改您的函数声明以使用timestamp：

CREATE OR REPLACE FUNCTION countStatistics(baselineDate timestamp)

PostgreSQL存储过程数据参数

1 个答案: