010_递归
010_递归
-- create Employees table and insert values
IF OBJECT_ID('Employees') IS NOT NULL
DROP TABLE Employees
GO
CREATE TABLE Employees
(
empid INT NOT NULL,
mgrid INT NULL,
empname VARCHAR(25) NOT NULL,
salary MONEY NOT NULL
)
GO
IF OBJECT_ID('Departments') IS NOT NULL
DROP TABLE Departments
GO
-- create Departments table and insert values
CREATE TABLE Departments
(
deptid INT NOT NULL PRIMARY KEY,
deptname VARCHAR(25) NOT NULL,
deptmgrid INT
)
GO
-- fill datas
INSERT INTO employees VALUES (1,NULL,'Nancy',00.00)
INSERT INTO employees VALUES (2,1,'Andrew',00.00)
INSERT INTO employees VALUES (3,1,'Janet',00.00)
INSERT INTO employees VALUES (4,1,'Margaret',00.00)
INSERT INTO employees VALUES (5,2,'Steven',00.00)
INSERT INTO employees VALUES (6,2,'Michael',00.00)
INSERT INTO employees VALUES (7,3,'Robert',00.00)
INSERT INTO employees VALUES (8,3,'Laura',00.00)
INSERT INTO employees VALUES (9,3,'Ann',00.00)
INSERT INTO employees VALUES (10,4,'Ina',00.00)
INSERT INTO employees VALUES (11,7,'David',00.00)
INSERT INTO employees VALUES (12,7,'Ron',00.00)
INSERT INTO employees VALUES (13,7,'Dan',00.00)
INSERT INTO employees VALUES (14,11,'James',00.00)
INSERT INTO departments VALUES (1,'HR',2)
INSERT INTO departments VALUES (2,'Marketing',7)
INSERT INTO departments VALUES (3,'Finance',8)
INSERT INTO departments VALUES (4,'R&D',9)
INSERT INTO departments VALUES (5,'Training',4)
INSERT INTO departments VALUES (6,'Gardening',NULL)
GO
SELECT * FROM employees
SELECT * FROM departments
-- table-value function
IF OBJECT_ID('fn_getsubtree') IS NOT NULL
DROP FUNCTION fn_getsubtree
GO
CREATE FUNCTION dbo.fn_getsubtree(@empid AS INT)
RETURNS TABLE
AS
RETURN(
WITH Employees_Subtree(empid, empname, mgrid, lvl)
AS
(
-- Anchor Member (AM)
SELECT empid, empname, mgrid, 0
FROM employees
WHERE empid = @empid
UNION ALL
-- Recursive Member (RM)
SELECT e.empid, e.empname, e.mgrid, es.lvl+1
FROM employees AS e
join employees_subtree AS es
ON e.mgrid = es.empid
)
SELECT * FROM Employees_Subtree
)
GO
-- cross apply query
SELECT *
FROM Departments AS D
CROSS APPLY fn_getsubtree(D.deptmgrid) AS ST
-- outer apply query
SELECT *
FROM Departments AS D
OUTER APPLY fn_getsubtree(D.deptmgrid) AS ST
SELECT *
FROM Departments d
OUTER APPLY (SELECT * FROM employees e WHERE d.deptmgrid=e.mgrid) q
select *from dbo.Customers as C outer apply
(select top 2 * from dbo.Orders as O
where C.customerid=O.customerid order by orderid desc) as CA
CREATE TABLE [aaa](
[id] [int] NULL,
[pid] [int] NULL,
[name] [nchar](10)
)
GO
INSERT INTO aaa VALUES(1,0,'a')
INSERT INTO aaa VALUES(2,0,'b')
INSERT INTO aaa VALUES(3,1,'c')
INSERT INTO aaa VALUES(4,1,'d')
INSERT INTO aaa VALUES(5,2,'e')
INSERT INTO aaa VALUES(6,3,'f')
INSERT INTO aaa VALUES(7,3,'g')
INSERT INTO aaa VALUES(8,4,'h')
GO
--下面的Sql是查询出1结点的所有子结点
with my1 as(select * from aaa where id = 1
union all select aaa.* from my1, aaa where my1.id = aaa.pid
)
select * from my1 --结果包含1这条记录，如果不想包含，可以在最后加上:where id <> 1
--下面的Sql是查询出8结点的所有父结点
with my1 as(select * from aaa where id = 8
union all select aaa.* from my1, aaa where my1.pid = aaa.id
)
select * from my1
--eg:
CREATE TABLE [tb](
[qj] [int] NULL, -- 月份，本测试假设从1月份开始，并且数据都是连续的月份，中间没有隔断
[je] [int] NULL, -- 本月销售实际金额
[rwe] [int] NULL, -- 本月销售任务额
[fld] [float] NULL -- 本月金额大于任务额时的返利点，返利额为je*fld
) ON [PRIMARY]
--现在要求计算每个月的返利金额，规则如下：
--1月份销售金额大于任务额 返利额=金额*返利点
--2月份销售金额大于任务额 返利额=（金额-1月份返利额）*返利点
--3月份销售金额大于任务额 返利额=（金额-1,2月份返利额）*返利点
--以后月份依次类推，销售额小于任务额时，返利为0
--具体的Sql如下：
WITH my1
AS ( SELECT * ,
CASE WHEN je > rwe THEN ( je * fld )
ELSE 0
END fle ,
CAST(0 AS FLOAT) tmp
FROM tb
WHERE qj = 1
UNION ALL
SELECT tb.* ,
CASE WHEN tb.je > tb.rwe
THEN ( tb.je - my1.fle - my1.tmp ) * tb.fld
ELSE 0
END fle ,
my1.fle + my1.tmp tmp -- 用于累加前面月份的返利
FROM my1 ,
tb
WHERE tb.qj = my1.qj + 1
)
SELECT *
FROM my1
*/