Mysql 从买卖交易日志中的每日库存

下面的SQL查询描述了两个表及其内容，这是大型库存系统的一个小而简化的部分

第一个是交易日志，列出各种物品的买卖数量

CREATE TABLE `Inventar_actions` (
  `PartID` char(8) NOT NULL,
  `DateSeq` smallint(4) unsigned NOT NULL,
  `ActionType` enum('Bought','Sold') NOT NULL,
  `Units` bigint(20) unsigned NOT NULL,
  PRIMARY KEY (`PartID`,`DateSeq`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `test`.`Inventar_actions` (`PartID`, `DateSeq`, `ActionType`, `Units`) VALUES 
('0001', '1020', 'Bought', '100'),('0001', '1025', 'Sold', '20'),('0001', '1028', 'Sold', '30'),
('0001', '1031', 'Bought', '100'),('0001', '1035', 'Sold', '50');

第二个表是日历，列出了任意历元的工作日及其序号：

CREATE TABLE `BusinessDates` (
  `DateSeq` int(10) unsigned NOT NULL,
  `BusinessDate` date NOT NULL,
  PRIMARY KEY (`DateSeq`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `test`.`BusinessDates` (`DateSeq`, `BusinessDate`) VALUES 
('1015', '2020-02-03'),('1016', '2020-02-04'),('1017', '2020-02-05'),('1018', '2020-02-06'),('1019', '2020-02-07'),
('1020', '2020-02-10'),('1021', '2020-02-11'),('1022', '2020-02-12'),('1023', '2020-02-13'),('1024', '2020-02-14'),
('1025', '2020-02-17'),('1026', '2020-02-18'),('1027', '2020-02-19'),('1028', '2020-02-20'),('1029', '2020-02-21'),
('1030', '2020-02-24'),('1031', '2020-02-25'),('1032', '2020-02-26'),('1033', '2020-02-27'),('1034', '2020-02-28'),
('1035', '2020-03-02'),('1036', '2020-03-03'),('1037', '2020-03-04'),('1038', '2020-03-05'),('1039', '2020-03-06')
;

我需要的是一份每日清单，看起来像这样：

| 1020 | 2020-02-10 | 100 | Bought | 100 |
| 1021 | 2020-02-11 |     |        | 100 |
| 1022 | 2020-02-12 |     |        | 100 |
| 1023 | 2020-02-13 |     |        | 100 |
| 1024 | 2020-02-14 |     |        | 100 |
| 1025 | 2020-02-17 |  20 | Sold   |  80 |
| 1026 | 2020-02-18 |     |        |  80 |
| 1027 | 2020-02-19 |     |        |  80 |
| 1028 | 2020-02-20 |  30 | Sold   |  50 |
| 1029 | 2020-02-21 |     |        |  50 |
| 1030 | 2020-02-24 |     |        |  50 |
| 1031 | 2020-02-25 | 100 | Bought | 150 |
| 1032 | 2020-02-26 |     |        | 150 |
| 1033 | 2020-02-27 |     |        | 150 |
| 1034 | 2020-02-28 |     |        | 150 |
| 1035 | 2020-03-02 |  50 | Sold   | 100 |
| 1036 | 2020-03-03 |     |        | 100 |
| 1037 | 2020-03-04 |     |        | 100 |
| 1038 | 2020-03-05 |     |        | 100 |
| 1039 | 2020-03-06 |     |        | 100 |

也就是说，对于每个营业日，考虑到购买和出售的零件，各方的余额是多少

我使用以下查询来排列日期、日期顺序和事务：

SELECT d.DateSeq, d.BusinessDate, a.`Units`, a.`ActionType` 
FROM `BusinessDates` AS d LEFT JOIN 
(SELECT DateSeq, ActionType, Units FROM `Inventar_actions` WHERE PartID = '0001') AS a USING (DateSeq)
WHERE d.DateSeq BETWEEN 1020 AND 1039
ORDER BY d.DateSeq;

这将生成所需输出的前四列

不幸的是，我找不到一个也会生成最后一列的查询，即零件的余额库存

请注意，有很多PartID和数千个工作日

---

请帮助…

这适用于mysql 5.x和8.0

小提琴

CREATE TABLE `Inventar_actions` (
  `PartID` char(8) NOT NULL,
  `DateSeq` smallint(4) unsigned NOT NULL,
  `ActionType` enum('Bought','Sold') NOT NULL,
  `Units` bigint(20) unsigned NOT NULL,
  PRIMARY KEY (`PartID`,`DateSeq`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `Inventar_actions` (`PartID`, `DateSeq`, `ActionType`, `Units`) VALUES 
('0001', '1020', 'Bought', '100'),('0001', '1025', 'Sold', '20'),('0001', '1028', 'Sold', '30'),
('0001', '1031', 'Bought', '100'),('0001', '1035', 'Sold', '50');

✓ ✓

CREATE TABLE `BusinessDates` (
  `DateSeq` int(10) unsigned NOT NULL,
  `BusinessDate` date NOT NULL,
  PRIMARY KEY (`DateSeq`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `BusinessDates` (`DateSeq`, `BusinessDate`) VALUES 
('1015', '2020-02-03'),('1016', '2020-02-04'),('1017', '2020-02-05'),('1018', '2020-02-06'),('1019', '2020-02-07'),
('1020', '2020-02-10'),('1021', '2020-02-11'),('1022', '2020-02-12'),('1023', '2020-02-13'),('1024', '2020-02-14'),
('1025', '2020-02-17'),('1026', '2020-02-18'),('1027', '2020-02-19'),('1028', '2020-02-20'),('1029', '2020-02-21'),
('1030', '2020-02-24'),('1031', '2020-02-25'),('1032', '2020-02-26'),('1033', '2020-02-27'),('1034', '2020-02-28'),
('1035', '2020-03-02'),('1036', '2020-03-03'),('1037', '2020-03-04'),('1038', '2020-03-05'),('1039', '2020-03-06')
;

✓ ✓

SELECT 
   d.DateSeq
   , d.BusinessDate
   , a.`Units`
   , a.`ActionType`
      , 
   CASE 
     WHEN a.`ActionType` = 'Bought' THEN @inventory := @inventory + a.`Units`
   WHEN a.`ActionType` = 'Sold' THEN @inventory := @inventory - a.`Units`
   ELSE
    @inventory := @inventory
   END inventory
FROM (SELECT * FROM `BusinessDates` ORDER BY  BusinessDate ASC) AS d LEFT JOIN 
(SELECT DateSeq, ActionType, Units FROM `Inventar_actions` WHERE PartID = '0001') AS a USING (DateSeq)
,(SELECT @inventory := 0) b
WHERE d.DateSeq BETWEEN 1020 AND 1039
ORDER BY d.DateSeq;

DateSeq | BusinessDate | Units | ActionType | inventory ------: | :----------- | ----: | :--------- | :-------- 1020 | 2020-02-10 | 100 | Bought | 100 1021 | 2020-02-11 | null | null | 100 1022 | 2020-02-12 | null | null | 100 1023 | 2020-02-13 | null | null | 100 1024 | 2020-02-14 | null | null | 100 1025 | 2020-02-17 | 20 | Sold | 80 1026 | 2020-02-18 | null | null | 80 1027 | 2020-02-19 | null | null | 80 1028 | 2020-02-20 | 30 | Sold | 50 1029 | 2020-02-21 | null | null | 50 1030 | 2020-02-24 | null | null | 50 1031 | 2020-02-25 | 100 | Bought | 150 1032 | 2020-02-26 | null | null | 150 1033 | 2020-02-27 | null | null | 150 1034 | 2020-02-28 | null | null | 150 1035 | 2020-03-02 | 50 | Sold | 100 1036 | 2020-03-03 | null | null | 100 1037 | 2020-03-04 | null | null | 100 1038 | 2020-03-05 | null | null | 100 1039 | 2020-03-06 | null | null | 100