遞歸sql查詢T-SQL

Question

我們如何在T-SQL中編寫遞歸sql查詢？ 你可以舉一個這樣的遞歸sql查詢的簡單例子。

Answer 1

CREATE TABLE ATable (ID INTEGER, ParentID INTEGER) 

INSERT INTO ATable 
SELECT 1, NULL 
UNION ALL SELECT 2, 1 
UNION ALL SELECT 3, 2 

;WITH q AS (
    SELECT ID, ParentID 
    FROM ATable 
    UNION ALL 
    SELECT a.ID, a.ParentID 
    FROM ATable a 
      INNER JOIN q ON q.ID = a.ParentID 
) 
SELECT DISTINCT * 
FROM q 

Answer 2

查看和閱讀：

Recursive Queries Using Common Table Expressions

Answer 3

請查看如何編寫遞歸查詢使用公用表表達式以下鏈接：http://msdn.microsoft.com/en-us/library/ms186243.aspx

Answer 4

這裏是一個自包含的例子。

Declare @Temp table 
(
    ID int, 
    ParentID int, 
    Happened date, 
    Value int 
) 
Insert into @Temp Values 
    (1, null, dateadd(day,1,GetDate()),1), 
    (2, 1, dateadd(day,2,GetDate()),2), 
    (3, 1, dateadd(day,3,GetDate()),3), 
    (4, null, dateadd(day,4,GetDate()),10), 
    (5, 3, dateadd(day,5,GetDate()),50), 
    (6, 4, dateadd(day,5,GetDate()),50), 
    (7, 5, dateadd(day,5,GetDate()),90); 
---------------------------------------- 

with Magic as 
(
    select * 
    from @Temp 
    Where ID = 1 

    union all 

    select t.* 
    from 
     Magic m 
     inner join 
     @Temp t 
      on t.ParentID = m.ID 
) 

select * from Magic 
option (maxrecursion 3)