如何编写可动态处理yearMo的SQL脚本（无需手动UNION）

我需要编写一段能动态处理yearMo值的SQL脚本，无需为每个年月和行号手动编写UNION语句。目前的代码在输入3个yearMo值时可以正常运行并得到正确结果，但需要实现数据的动态获取。

现有代码 #

WITH NumberedRows AS (
    SELECT
        studyid,
        enroll_flag,
        yearMo,
        ROW_NUMBER() OVER (PARTITION BY yearMo, studyid ORDER BY studyid) AS rn
    FROM xyz -- 替换为实际表名
),
YearMoValues AS (
   SELECT DISTINCT yearMo,
    ROW_NUMBER() OVER (ORDER BY yearMo) AS rn
    FROM xyz
    Group by yearMo
    )

SELECT nr.studyid,
    MAX(CASE WHEN nr.yearMo = ymv.yearMo AND nr.rn = 1 and ymv.rn=1 THEN nr.enroll_flag END) AS [201301],
    MAX(CASE WHEN nr.yearMo = ymv.yearMo AND nr.rn = 1 and ymv.rn=2 THEN nr.enroll_flag END) AS [201302],
    MAX(CASE WHEN nr.yearMo = ymv.yearMo AND nr.rn = 1 and ymv.rn=3 THEN nr.enroll_flag END) AS [201303]
FROM NumberedRows nr
JOIN YearMoValues ymv ON nr.yearMo = ymv.yearMo
GROUP BY nr.studyid,nr.rn
HAVING nr.rn = 1
UNION
SELECT nr.studyid,
    MAX(CASE WHEN nr.yearMo = ymv.yearMo AND nr.rn = 2 and ymv.rn=1 THEN nr.enroll_flag END) AS [201301],
    MAX(CASE WHEN nr.yearMo = ymv.yearMo AND nr.rn = 2 and ymv.rn=2 THEN nr.enroll_flag END) AS [201302],
    MAX(CASE WHEN nr.yearMo = ymv.yearMo AND nr.rn = 2 and ymv.rn=3 THEN nr.enroll_flag END) AS [201303]
FROM NumberedRows nr
JOIN YearMoValues ymv ON nr.yearMo = ymv.yearMo
GROUP BY nr.studyid,nr.rn
HAVING nr.rn = 2;

输入数据 #

预期输出 #

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