报表完成前，最大recursion100已经耗尽

我不断收到此查询最大recursion错误。

起初我以为这是因为一个null被返回，然后它会尝试匹配导致错误的空值，然而，我重写了我的查询，所以空值不返回，错误仍然发生。

重写这个函数的最好方法是什么，这样就不会发生错误

WITH EmployeeTree AS ( SELECT EMP_SRC_ID_NR Id, USR_ACV_DIR_ID_TE Uuid, CASE Employees.APV_MGR_EMP_ID WHEN Null THEN '0' ELSE Employees.APV_MGR_EMP_ID END as ApprovalManagerId FROM dbo.[tEmployees] as Employees WITH (NOLOCK) WHERE APV_MGR_EMP_ID = @Id and Employees.APV_MGR_EMP_ID is not null and Employees.EMP_SRC_ID_NR is not null UNION ALL SELECT EMP_SRC_ID_NR Id, USR_ACV_DIR_ID_TE Uuid, CASE Employees.UPS_ACP_EMP_NR WHEN Null THEN '1' ELSE Employees.UPS_ACP_EMP_NR END as ApprovalManagerId FROM dbo.[tEmployees] as Employees WITH (NOLOCK) WHERE UPS_ACP_EMP_NR = @Id and Employees.APV_MGR_EMP_ID is not null and Employees.EMP_SRC_ID_NR is not null UNION ALL SELECT Employees.EMP_SRC_ID_NR, Employees.USR_ACV_DIR_ID_TE, CASE Employees.APV_MGR_EMP_ID WHEN Null THEN '2' ELSE Employees.APV_MGR_EMP_ID END FROM dbo.[tEmployees] as Employees WITH (NOLOCK) JOIN EmployeeTree ON Employees.APV_MGR_EMP_ID = EmployeeTree.Id where Employees.APV_MGR_EMP_ID is not null and Employees.EMP_SRC_ID_NR is not null ) SELECT Id AS [EmployeeId], Uuid AS [EmployeeUuid], ApprovalManagerId AS [ManagerId] FROM EmployeeTree 

Answer 1

在查询的末尾指定maxrecursion选项 ：

 ... from EmployeeTree option (maxrecursion 0) 

这允许您指定在发生错误之前CTE可以recursion的频率。 Maxrecursion 0允许无限recursion。

Answer 2

这只是一个避免最大recursion错误的例子。 我们必须使用选项（maxrecursion 365）; 或选项（maxrecursion 0）;

 DECLARE @STARTDATE datetime; DECLARE @EntDt datetime; set @STARTDATE = '01/01/2009'; set @EntDt = '12/31/2009'; declare @dcnt int; ;with DateList as ( select @STARTDATE DateValue union all select DateValue + 1 from DateList where DateValue + 1 < convert(VARCHAR(15),@EntDt,101) ) select count(*) as DayCnt from ( select DateValue,DATENAME(WEEKDAY, DateValue ) as WEEKDAY from DateList where DATENAME(WEEKDAY, DateValue ) not IN ( 'Saturday','Sunday' ) )a option (maxrecursion 365);