SQL Server : Using recursive CTE to resolve group membership

我有一张 table (users_groups):

+-----------+------------+---------+
| groupGUID | memberGUID | isGroup |
+-----------+------------+---------+
|  32AB160C |   5B277276 |       0 |
|  32AB160C |   0A023D1D |       0 |
|  5C952B2E |   32AB160C |       1 |
|  4444FTG5 |   5C952B2E |       1 |
+-----------+------------+---------+

isGroup列指示memberGUID是否为组。

我想获得一个新表(new_users_groups)，所有组成员身份都已解决:

+-----------+------------+
| groupGUID | memberGUID |
+-----------+------------+
|  32AB160C |   5B277276 |
|  32AB160C |   0A023D1D |
|  5C952B2E |   5B277276 |
|  5C952B2E |   0A023D1D |
|  4444FTG5 |   5B277276 |
|  4444FTG5 |   0A023D1D |
+-----------+------------+

现在，我正在手动做所有事情:

寻找所有群组的memberGUID
SELECT * FROM users_groups WHERE isGroup = 1;

对于上一步返回的所有组，请找到其成员
SELECT * FROM users_groups WHERE groupGUID = '5C952B2E'

如果成员不是组，请将其插入新表
INSERT INTO new_users_groups (groupGUID, memberGUID) VALUES ('5C952B2E', '5B277276'); INSERT INTO new_users_groups (groupGUID, memberGUID) VALUES ('5C952B2E', '0A023D1D');

如果成员是组，请转到步骤2。

我该如何自动化呢？也许使用递归CTE？

最佳答案

您可以使用递归CTE进行此操作:

with cte as (
  select ug.groupGUID, ug.groupGUID as grp, ug.memberGUID
  from user_groups ug
  where isGroup = 0
  union all
  select ug.groupGUID, ug.groupGUID as grp, cte.memberGUID
  from user_groups ug join
       cte
       on cte.grp = ug.memberGUID
 )
select groupGUID, memberGUID
from cte;

这是一个Rextester。