复杂的SQL查询-计数始终返回0

Question

我想计算每个月有多少用户创建帐户，我在这里找到一个查询-作者说它对他有效，但是我有问题-正如我所说的-第3个参数始终为0。

我试图通过多种方式（删除，添加args）对其进行修复，但结果相同或SQL错误。

SELECT y, m, Count(ytskagamerpl_userinfo.creationdate)
FROM (
      SELECT y, m
      FROM
         (SELECT YEAR(CURDATE()) y UNION ALL SELECT YEAR(CURDATE())-1) years,
         (SELECT 1 m UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4
           UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8
           UNION ALL SELECT 9 UNION ALL SELECT 10 UNION ALL SELECT 11 UNION ALL SELECT 12) months
    ) ym
LEFT JOIN ytskagamerpl_userinfo
    ON ym.y = YEAR(FROM_UNIXTIME(ytskagamerpl_userinfo.creationdate))
    AND ym.m = MONTH(FROM_UNIXTIME(ytskagamerpl_userinfo.creationdate))
WHERE (y=YEAR(CURDATE()) AND m<=MONTH(CURDATE()))
      OR
      (y<YEAR(CURDATE()) AND m>MONTH(CURDATE()))
GROUP BY y, m;

数据库：

uid | creationdate (TIMESTAMP):
1   | 20.10.2018
2   | 12.11.2018
... | ..........
X   | 15.07.2019

PHP VAR DUMP _ https://pastebin.com/ABT5PCZn

我希望在X月201X年创建的用户数，但始终返回0， 年和月正确显示。