Sql 具有2个并集的公用表表达式计数器

如果我对一个有母亲和父亲的家庭有一个通用的表表达式，我如何增加“世代”计数器？一个家庭应该将孩子作为第0代，父母作为第1代，四位祖父母作为第2代。但是循环执行两次，每组祖父母执行一次

;WITH FamilyTree
AS
(
    SELECT *, 0 AS Generation
    FROM myTable
    WHERE [id] = 99

    UNION ALL
    SELECT name, Generation + 1
    FROM myTable AS Fam
    INNER JOIN FamilyTree
    ON Fam.[id] = FamilyTree.[motherid]

    UNION ALL
    SELECT name, Generation + 1
    FROM myTable AS Fam
    INNER JOIN FamilyTree
    ON Fam.[id] = FamilyTree.[fatherid]
)
SELECT generation, name FROM FamilyTree 

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在一次过的一个代沟中更改连接查看亲属，而不是在CTE中使用2个递归子句。这两个子句构成了一个部分交叉联接，这就是为什么会有额外的行

;WITH FamilyTree
AS
(
    SELECT *, 0 AS Generation
    FROM myTable
    WHERE [id] = 99

    UNION ALL
    SELECT name, Generation + 1
    FROM myTable AS Fam
    INNER JOIN FamilyTree
    ON Fam.[id] IN (FamilyTree.[motherid], FamilyTree.[fatherid])
)
SELECT generation, name FROM FamilyTree