SQL Server中的递归CTE查询

Question

我已经在此站点上查看了许多递归CTE示例，并且尝试将其应用于我自己的数据。 与大多数示例相比，我似乎拥有更多的联接，但我认为我能到达那里。 我需要帮助的问题是我收到一条错误消息：

声明终止。 在语句完成之前，最大递归100已用尽。

我已经运行了CTE的第一条select语句，并且我已经反复运行了第二条select语句（具有不同的实际职位代码），并且对于该员工有六个级别，因此我看不到为什么会出错。

我的一个怀疑领域是我必须应用标准'relationship_type_id = 0'，因为这是'Reports To'关系类型。 我曾尝试将其设为左外部联接，但不允许这样做。 这意味着我不会使用此查询来获得最高级别的经理（即本身没有经理的人）。

我已经在下面发布了代码，任何帮助将不胜感激。

WITH EmployeeHierarchy (EmployeeID, LastName, FirstName, PositionCode, ReportsTo, HierarchyLevel) AS 
(
   SELECT 
      p.employee_id as EmployeeID,
      p.last_name as LastName,
      p.first_name as FirstName,
      pos.position_code as PositionCode,
      r.to_position_code as ReportsTo,
      1 as HierarchyLevel
   FROM 
       --JOIN: Personal details
       dbo.person p
   --JOIN: Employment links a person to a post (could have more than one)
   INNER JOIN 
       dbo.employment e ON e.employee_id = p.employee_id
   --JOIN: details of the position held
   INNER JOIN 
       dbo.position pos ON pos.position_code = e.position_code
   --JOIN: Relationships between the positions, one position reports to another position etc.
   --      There are several 'relationship types', we are only interested in relationship_type_id = 0 
   --      as this is the 'Reports to' relationship code.  Others types include 'Managed by' etc.
   INNER JOIN 
       dbo.relationship r ON r.from_position_code = pos.position_code AND r.relationship_type_id = 0
   WHERE 
       --CRITERIA: Use my employee Id as a starting point for testing
       p.employee_id = '10076395'

   UNION ALL

   -- Recursive step
   SELECT 
       p2.employee_id as EmployeeID,
       p2.last_name as LastName,
       p2.first_name as FirstName,
       pos2.position_code as PositionCode,
       r2.to_position_code as ReportsTo,
       eh.HierarchyLevel + 1 AS HierarchyLevel
   FROM 
       dbo.person p2
   INNER JOIN 
       dbo.employment e2 ON e2.employee_id = p2.employee_id
   INNER JOIN 
       dbo.position pos2 ON pos2.position_code = e2.position_code
   INNER JOIN 
       dbo.relationship r2 ON r2.from_position_code = pos2.position_code AND r2.relationship_type_id = 0
   --JOIN: Link this query back to the base query
   INNER JOIN 
       EmployeeHierarchy eh ON r2.from_position_code = eh.PositionCode
)
SELECT *
FROM EmployeeHierarchy
ORDER BY HierarchyLevel, LastName, FirstName 

Answer 1

请试试 ：

WITH EmployeeHierarchy (EmployeeID, LastName, FirstName, PositionCode, ReportsTo, HierarchyLevel) AS 
(
SELECT 
    p.employee_id as EmployeeID,
    p.last_name as LastName,
    p.first_name as FirstName,
    pos.position_code as PositionCode,
    r.to_position_code as ReportsTo,
    1 as HierarchyLevel
FROM 
    --JOIN: Personal details
    dbo.person p

    --JOIN: Employment links a person to a post (could have more than one)
    INNER JOIN dbo.employment e
    ON e.employee_id = p.employee_id

    --JOIN: details of the position held
    INNER JOIN dbo.position pos 
    ON pos.position_code = e.position_code

    --JOIN: Relationships between the positions, one position reports to another position etc.
    --      There are several 'relationship types', we are only interested in relationship_type_id = 0 
    --      as this is the 'Reports to' relationship code.  Others types include 'Managed by' etc.
    INNER JOIN dbo.relationship r
    ON  r.from_position_code = pos.position_code
        and r.relationship_type_id = 0
WHERE 
    --CRITERIA: Use my employee Id as a starting point for testing
    p.employee_id = '10076395'

UNION ALL
-- Recursive step
SELECT 
    p2.employee_id as EmployeeID,
    p2.last_name as LastName,
    p2.first_name as FirstName,
    pos2.position_code as PositionCode,
    r2.to_position_code as ReportsTo,
    eh.HierarchyLevel + 1 AS HierarchyLevel
 FROM 
    dbo.person p2

    INNER JOIN dbo.employment e2
    ON e2.employee_id = p2.employee_id

    INNER JOIN dbo.position pos2 
    ON pos2.position_code = e2.position_code

    INNER JOIN dbo.relationship r2
    ON  r2.from_position_code = pos2.position_code
        and r2.relationship_type_id = 0

    --JOIN: Link this query back to the base query
    INNER JOIN EmployeeHierarchy eh 
    ON r2.from_position_code = eh.ReportsTo
)
SELECT *
FROM EmployeeHierarchy
ORDER BY HierarchyLevel, LastName, FirstName 

Answer 2

试试看。

我已将复杂的联接移至单独的CTE，以保持递归部分尽可能简洁。 如果没有其他方法，这种方法应该可以帮助您查明问题。

; WITH employees AS (
  SELECT person.employee_id
       , person.last_name
       , person.first_name
       , position.position_code
       , relationship.to_position_code
  FROM   dbo.person
   INNER
    JOIN dbo.employment
      ON employment.employee_id = person.employee_id
   INNER
    JOIN dbo.position
      ON position.position_code = employment.position_code
   INNER
    JOIN dbo.relationship
      ON relationship.from_position_code = position.position_code
     AND relationship.relationship_type_id = 0
)
, recursive_bit AS (
  SELECT employee_id
       , last_name
       , first_name
       , position_code
       , to_position_code
  FROM   employees
  WHERE  employee_id = '10076395'

    UNION ALL

      SELECT employees.employee_id
           , employees.last_name
           , employees.first_name
           , employees.position_code
           , employees.to_position_code
      FROM   recursive_bit
       INNER
        JOIN employees
          ON employees.position_code = recursive_bit.to_position_code
)
SELECT *
FROM   recursive_bit