Question

如果我有这样的递归CTE，我如何将结果存储在变量中？

protoc [other-options] some.proto

我已尝试过以下内容，但SSMS抱怨两个选项中的语法：

WITH MyCTE (ChildID, ParentID)
AS
(
   SELECT ID, ParentID From MyTable
    WHERE ID = 1
   UNION ALL
    SELECT MT.ID, MT.ParentID 
    FROM MyCTE Child
    JOIN MyTable MT ON MT.ID = Child.ParentID
    WHERE Child.ParentID IS NOT NULL
)
SELECT COUNT(*)
FROM MyCTE
OPTION (MAXRECURSION 20)

和

DECLARE @numberOfRecords int = (
WITH MyCTE (ChildID, ParentID)
AS
(
   SELECT ID, ParentID From MyTable
    WHERE ID = 1
   UNION ALL
    SELECT MT.ID, MT.ParentID 
    FROM MyCTE Child
    JOIN MyTable MT ON MT.ID = Child.ParentID
    WHERE Child.ParentID IS NOT NULL
)
SELECT COUNT(*)
FROM MyCTE
OPTION (MAXRECURSION 20))

Answer 1

您可以先声明变量然后再分配它：

DECLARE @numberOfRecords int;

WITH MyCTE (ChildID, ParentID) AS (
      SELECT ID, ParentID
      FROM MyTable
      WHERE ID = 1
      UNION ALL
      SELECT MT.ID, MT.ParentID 
      FROM MyCTE Child JOIN
           MyTable MT
           ON MT.ID = Child.ParentID
      WHERE Child.ParentID IS NOT NULL
     )
SELECT @numberOfRecords = COUNT(*)
FROM MyCTE
OPTION (MAXRECURSION 20);

如何在SQL中存储递归CTE的结果？

1 个答案: