SQL父子查询不起作用

Question

我想获取父母及其子女的数据，意味着首先要成为父母，然后是他们的子女，以下是我要转换为父母及其子女的查询

SELECT a.FactorTitle,
       a.FactorCode,
       a.parentId,
       c.FactorColumnCode,
       c.FactorColumnTitle,
       c.FactorColumnValue,
       c.isFactorValue,
       c.FieldType,

  (SELECT count(*)
   FROM FactorSetup
   WHERE parentId=a.FactorCode) AS childCount
FROM FactorSetup a
INNER JOIN PDModelSetup b ON a.PDModelCode=b.PDModelCode
LEFT JOIN FactorColumnSetup c ON a.FactorCode=c.FactorCode
WHERE a.PDModelCode=2
  AND c.isFactorValue <> 'Y'
  AND a.FactorType='4'

我在下面查询

WITH EntityChildren AS
  (
   SELECT  a.FactorTitle,
           a.FactorCode,
           a.parentId,
           c.FactorColumnCode,
           c.FactorColumnTitle,
           c.FactorColumnValue,
           c.isFactorValue,
           c.FieldType,

  (SELECT count(*)
   FROM FactorSetup
   WHERE parentId=a.FactorCode) AS childCount
   FROM FactorSetup a
   LEFT JOIN FactorColumnSetup c ON a.FactorCode=c.FactorCode
   UNION ALL 
   SELECT a.FactorTitle,
           a.FactorCode,
           a.parentId,
           c.FactorColumnCode,
           c.FactorColumnTitle,
           c.FactorColumnValue,
           c.isFactorValue,
           c.FieldType,

  (SELECT count(*)
   FROM FactorSetup
   WHERE parentId=a.FactorCode) AS childCount
   FROM FactorSetup a

   INNER JOIN EntityChildren e2 ON a.parentId = e2.FactorCode
   LEFT JOIN FactorColumnSetup c ON a.FactorCode=c.FactorCode
   )

SELECT * FROM EntityChildren

执行这些查询后，我得到了这个错误

Msg 467, Level 16, State 1, Line 1
GROUP BY, HAVING, or aggregate functions are not allowed in the recursive part of a recursive common table expression 'EntityChildren'.
Msg 462, Level 16, State 1, Line 1
Outer join is not allowed in the recursive part of a recursive common table expression 'EntityChildren'.

然后我更改查询并删除co​​unt（*）

WITH EntityChildren AS
  (
   SELECT  a.FactorTitle,
           a.FactorCode,
           a.parentId,
           c.FactorColumnCode,
           c.FactorColumnTitle,
           c.FactorColumnValue,
           c.isFactorValue,
           c.FieldType
   FROM FactorSetup a
   LEFT JOIN FactorColumnSetup c ON a.FactorCode=c.FactorCode
   UNION ALL 
   SELECT a.FactorTitle,
           a.FactorCode,
           a.parentId,
           c.FactorColumnCode,
           c.FactorColumnTitle,
           c.FactorColumnValue,
           c.isFactorValue,
           c.FieldType
   FROM FactorSetup a

   INNER JOIN EntityChildren e2 ON a.parentId = e2.FactorCode
   LEFT JOIN FactorColumnSetup c ON a.FactorCode=c.FactorCode
   )

SELECT * FROM EntityChildren 

然后我得到这个错误

Msg 462, Level 16, State 1, Line 1
Outer join is not allowed in the recursive part of a recursive common table expression 'EntityChildren'.

Answer 1

实际上，这是设计使然 ，请阅读《定义和使用递归公用表表达式的准则》。

递归成员的CTE_query_definition中不允许以下各项：

• 选择地区
• 通过...分组
• HAVING
• 标量聚集
• 最佳
• 左，右，外联接（允许内联接）
• 子查询

您必须将LEFT JOIN和COUNT移出CTE查询，将这些数据存储在其他位置（例如在临时表中），然后再将它们与CTE查询的结果一起使用。 或者，您可以避免CTE查询，并针对每个级别的父子对象分别进行此步骤，将其存储在单独的临时表中并使用结果。 希望能有所帮助。