MYSQL数据累加

• 需求

查询小说发布到50000字记录的章节信息

• 章节表

CREATE TABLE `t_chapter` (
  `id` varchar(255) NOT NULL COMMENT '主键',
  `num` int(11) DEFAULT NULL COMMENT '发布字数',
  `production_number` varchar(11) NOT NULL COMMENT '作品编号',
  `pub_time` datetime DEFAULT NULL COMMENT '发布时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

• 思路：

章节信息按照发布时间排序，使用mysql自定义变量特性进行累加

• SQL实现

        SELECT
            id ,
            a.auto_code AS autoCode ,
            a.production_number AS productionNumber ,
            a.pub_time AS pubTime ,
            a.num ,
            (@sumSalary := @sumSalary + num) AS count
        FROM
            t_chapter a ,
            (SELECT @sumSalary := 0) b
        WHERE
            a.production_number = 1414(作品编号)
        ORDER BY
            a.pub_time ASC

查询结果如下：

• 添加条件count大于等于50000取第一条

        SELECT
            *
        FROM
        ( SELECT
            id ,
            a.auto_code AS autoCode ,
            a.production_number AS productionNumber ,
            a.pub_time AS pubTime ,
            a.num ,
            (@sumSalary := @sumSalary + num) AS count
        FROM
            t_chapter a ,
            (SELECT @sumSalary := 0) b
        WHERE
            a.production_number = 1414
        ORDER BY
            a.pub_time ASC
            ) AS p
        WHERE
            count >= 50000 LIMIT 0,1;

• 不了解@MYSQL自定义变量可以参考：

  MYSQL自定义变量