MySQL按周统计 WEEK 实例 - 水木山川

MySQL周统计，MySQL函数WEEK，subdate，date_format，date_sub，date_add用法

MySQL按周统计每周数据总和，用到了WEEK，subdate，date_format，date_sub，date_add函数。

　　WEEK() 查看给定日期周数，语法：WEEK(date, mode);

　　SUBDATE() 函数做日期减法操作，语法：SUBDATE(date,INTERVAL expr unit) 和 SUBDATE(expr,days);

　　DATE_FORMAT() 函数用于以不同的格式显示日期/时间数据，语法：DATE_FORMAT(date,format);

　　DATE_SUB() 函数从日期减去指定的时间间隔，语法：DATE_SUB(date,INTERVAL expr type);

　　DATE_ADD() 函数向日期添加指定的时间间，语法：DATE_ADD(date,INTERVAL expr type);

样例数据：

-- 创建数据样例表
CREATE TABLE `day_weight_tb` (
  `day_date` varchar(16) DEFAULT NULL,
  `in_weight` varchar(64) DEFAULT NULL,
  `out_weight` varchar(64) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- 插入样例数据
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2018-03-10\', \'18.84\', \'74.14\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-21\', \'17.69\', \'25.97\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-02-01\', \'16.48\', \'10.0\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-29\', \'10.9\', \'74.12\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-02-13\', \'15.25\', \'16.62\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-12\', \'19.21\', \'95.42\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-02-14\', \'26.38\', \'20.59\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-24\', \'15.99\', \'16.823\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-13\', \'94.846\', \'56.256\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-03-03\', \'15.63\', \'12.128\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-03-12\', \'14.282\', \'24.046\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-16\', \'14.045\', \'11.73\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-03-08\', \'23.41\', \'23.441\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-31\', \'11.177\', \'4332.26\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-01-23\', \'11.8\', \'17104.49\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-03-17\', \'17.95\', \'13.81\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-03-01\', \'19.23\', \'20.43\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-02-05\', \'21.55\', \'51.0\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-02-27\', \'13.003\', \'23.32\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-03-11\', \'16.44\', \'24.44\');
INSERT INTO `day_weight_tb` (`day_date`, `in_weight`, `out_weight`) VALUES (\'2019-02-28\', \'16.48\', \'23.4\');

-- 创建结果表，插入统计结果
drop TABLE if exists week_count_tb;
CREATE TABLE `week_count_tb` (
  `week_day` varchar(32) DEFAULT NULL,
  `week_num` varchar(32) DEFAULT NULL,
  `in_weight` varchar(64) DEFAULT NULL,
  `out_weight` varchar(64) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

delete from week_count_tb;
INSERT INTO week_count_tb 
SELECT
    *
FROM
    (
        SELECT
            middle.week_day,
            middle.week_num,
            sum(in_weight) in_weight,
            sum(out_weight) out_weight
        FROM
            (
                SELECT
                    subdate(
                        date_sub(day_date, INTERVAL 1 DAY),
                        date_format(date_sub(day_date, INTERVAL 1 DAY),\'%w\') - 7) week_day,
                    WEEK (
                        date_add(subdate(
                                date_sub(day_date, INTERVAL 1 DAY),
                                date_format(date_sub(day_date, INTERVAL 1 DAY),\'%w\') - 7),INTERVAL 6 DAY),2) week_num,
                    in_weight,
                    out_weight
                FROM
                    day_weight_tb
            ) middle
        GROUP BY
            week_day,
            week_num
    ) result;

思路：先确定一天是属于一年中的具体周数，再获取到一周中的周末日期，最后根据周数分组求和。