来自分层数据库表的 SQL 计数子项

Question

我有一个分层数据库表，其中包含上述数组中的成员，包括父项和子项（mlm 结构/树）。

表名是成员，表中的字段是上述数组中的元素（userid、referenceid、name、surrname）。

如何计算一个用户 ID 的所有孩子？让我们以userid = 5 有孩子一个孩子有孩子为例。

我希望 SQL 代码将用户 ID 计算为所有子项和子项。

谢谢！

Array
(
[0] => Array
    (
        [userid] => 3
        [referenceid] => 4
        [name] => Bandil
        [surname] => Kazim
    )

[1] => Array
    (
        [userid] => 1
        [referenceid] => 2
        [name] => Zarki
        [surname] => Andrew
    )

[2] => Array
    (
        [userid] => 5
        [referenceid] => 1
        [name] => Mirko
        [surname] => Paul
    )

[3] => Array
    (
        [userid] => 2390189598
        [referenceid] => 5
        [name] => Matias
        [surname] => Clark
    )

[4] => Array
    (
        [userid] => 4
        [referenceid] => 
        [name] => Duncan
        [surname] => Christoph
    )

[5] => Array
    (
        [userid] => 2
        [referenceid] => 3
        [name] => Zar
        [surname] => Jamal
    )

[6] => Array
    (
        [userid] => 123123
        [referenceid] => 5
        [name] => Victor
        [surname] => Dobrinski
    )

[7] => Array
    (
        [userid] => 9
        [referenceid] => 2390189598
        [name] => Slav
        [surname] => Jorgasen
    )

[8] => Array
    (
        [userid] => 4057926110
        [referenceid] => 5
        [name] => Joseph
        [surname] => Vladinski
    )

[9] => Array
    (
        [userid] => 10
        [referenceid] => 2390189598
        [name] => Jala
        [surname] => David
    )

[10] => Array
    (
        [userid] => 7568954902
        [referenceid] => 4057926110
        [name] => ohn
        [surname] => macaron
    )
)

Answer 1

如果 REFERENCEID 是父亲的 ID，这是一种方式

SELECT 
    REFERENCEID, COUNT(*)
FROM
    (SELECT 
         USERID, REFERENCEID 
     FROM 
         MEMBERS
     WHERE 
         REFERENCEID IS NOT NULL
     UNION
     SELECT 
         B.USERID AS USERID, A.REFERENCEID AS REFERENCEID
     FROM 
         MEMBERS A
     LEFT JOIN 
         MEMBERS B ON A.USERID = B.REFERENCEID
     WHERE 
         B.USERID IS NOT NULL AND A.REFERENCEID IS NOT NULL) TOT
GROUP BY 
    REFERENCEID;

结果是每个REFERENCEID的儿子和侄子的计数；如果你想通过REFERENCEID在联合中使用的两个集合上知道儿子的数量和侄子的数量。