在MySQL中计算每月已开启项目的库存数

我在编写该查询语句时遇到了困难，提前感谢您的帮助！现有一组带有开启日期（OpenDate）和关闭日期（CloseDate）的项目，我需要计算每个月份的已开启项目库存数，即月末前尚未关闭的所有项目数量。

预期结果 #

使用环境 #

• MySQL 5.7.44-log
• 已禁用ONLY_FULL_GROUP_BY

测试数据 #

CREATE TABLE TestDate 
(
    Objectid int,
    OpenDate date NULL,
    CloseDate date NULL
);

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (1, '2013-02-18 00:00:00', '2013-02-19 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (2, '2013-01-22 00:00:00', '2013-01-28 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (3, '2012-10-17 00:00:00', '2013-02-01 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (4, '2012-10-28 00:00:00', '2012-12-14 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (5, '2013-01-16 00:00:00', '2013-02-02 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (6, '2013-01-20 00:00:00', '2013-01-25 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (7, '2012-11-25 00:00:00', '2012-12-04 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (8, '2012-10-20 00:00:00', '2013-02-04 00:00:00');

INSERT INTO TestDate (Objectid, OpenDate, CloseDate) 
VALUES (9, '2012-10-31 00:00:00', '2012-11-15 00:00:00');

我尝试过Stack Overflow上的多种方法，但均未得到预期结果。

内容的提问来源于stack exchange，提问作者user3099631