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我试图从我的数据库中获取具有不同日期时间戳的值的总和。我的目标是返回该日期表中所有值的每一天的总数。我的商店过程如下所示：

DELIMITER //
DROP PROCEDURE get_reads;
CREATE PROCEDURE get_reads (IN  device varchar (20), IN start_date datetime, IN end_date datetime, IN read_type varchar(8))

BEGIN

    SELECT dr.date_time, sum(dr.device_reading)
    FROM DEVICE_DETAILS dd,
    DEVICE_READING dr
    WHERE dr.device_id = dd.device_id
    AND dd.serial_number = device
    AND dr.date_time BETWEEN start_date AND end_date
    AND dr.reading_type = read_type;



END//

我相信我将不得不使用临时表或其他东西，但在网上找不到任何关于我的情况的建议。对于每一天，我每半小时都有一个值，我希望存储的 porocedure 在我的日期范围内返回每天的总计传入。数据库列看起来像这样

+-----------+---------------------+--------------+----------------+-------+
| device_id | date_time           | reading_type | device_reading | units |
+-----------+---------------------+--------------+----------------+-------+
| E1        | 2012-11-19 00:29:00 | Profile      |   0.0719131800 | KW    |
| E1        | 2012-11-19 00:59:00 | Profile      |   0.0802306700 | KW    |
| E1        | 2012-11-19 01:29:00 | Profile      |   0.0767434100 | KW    |
| E1        | 2012-11-19 01:59:00 | Profile      |   0.0737920500 | KW    |
| E1        | 2012-11-19 02:29:00 | Profile      |   0.0794256700 | KW    |
| E1        | 2012-11-19 02:59:00 | Profile      |   0.0729868200 | KW    |
| E1        | 2012-11-19 03:29:00 | Profile      |   0.0745970500 | KW    |
| E1        | 2012-11-19 03:59:00 | Profile      |   0.0804993100 | KW    |
| E1        | 2012-11-19 04:29:00 | Profile      |   0.0837193100 | KW    |
| E1        | 2012-11-19 04:59:00 | Profile      |   0.0483004600 | KW    |
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1 回答 1

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使用 CAST(datetime AS DATE) 解决；

DELIMITER //
DROP PROCEDURE get_reads;
CREATE PROCEDURE get_reads (IN  device varchar (20), IN start_date datetime, IN end_date datetime, IN read_type varchar(8))

    BEGIN

            SELECT dr.date_time, sum(dr.device_reading)
            FROM DEVICE_DETAILS dd,
            DEVICE_READING dr
            WHERE dr.device_id = dd.device_id
            AND dd.serial_number = device
            AND dr.date_time BETWEEN start_date AND end_date
            AND dr.reading_type = read_type
            GROUP BY CAST(dr.date_time AS DATE);



    END//
于 2013-02-28T15:29:38.777 回答