SQL Server 2008程序设计之 cte递归查询中限制递归层次，PIVOT和UNPIVOT表旋转的应用
--SQL Server 2008程序设计之 cte递归查询中限制递归层次，PIVOT和UNPIVOT表旋转的应用
/********************************************************************************
*主题：SQL Server 2008程序设计之
*说明：本文是个人学习的一些笔记和个人愚见
* 有很多地方你可能觉得有异议，欢迎一起讨论
*作者：Stephenzhou(阿蒙)
*日期: 2012.12.3
*Mail:[email protected]
*另外：转载请著名出处。
**********************************************************************************/
--精通Sql2008 程序设计
--cte查询
--如下表
--如下表 /* SELECT * FROM employeetree employeeid employeename reportsto ----------- -------------------------------------------------- ----------- 1 Richard NULL 2 Stephen 1 3 Clemens 2 4 Malek 2 5 Goksin 4 6 Kimberly 1 7 Ramesh 5 (7 行受影响) */
--找出Stephen下面的员工和对应的领导
;with ct as ( select * from employeetree where employeeid=2 union all select e.* from employeetree e inner join ct c on e.reportsto=c.employeeid ) select c.employeename,e.employeename from ct c join employeetree e on c.reportsto=e.employeeid /* employeename employeename -------------------------------------------------- -------------------------------------------------- Stephen Richard Clemens Stephen Malek Stephen Goksin Malek Ramesh Goksin (5 行受影响) */
--option (maxrecursion 25)
;with ct as ( select * from employeetree where employeeid=2 union all select e.* from employeetree e inner join ct c on e.reportsto=c.employeeid ) select c.employeename,e.employeename from ct c join employeetree e on c.reportsto=e.employeeid option(maxrecursion 2) /* employeename employeename -------------------------------------------------- -------------------------------------------------- Stephen Richard Clemens Stephen Malek Stephen Goksin Malek 消息 530，级别 16，状态 1，第 1 行 语句被终止。完成执行语句前已用完最大递归 2。 */
--说明：在开发中，有递归的限制，默认的限制为100 如果超过100 必须设置 option(Maxrecursion 0) 没有最大的限制
--但是一般在开发中不需要限制这个递归的层次，只需要在后面跟个where来限制需要的层次就好了
--PIVOT 和UNPIVOT运算符
create table VendorEmployee ( VendorID int, Emp1orders int, Emp2Orders int, Emp3Orders int, Emp4Orders int, Emp5Orders int ) go insert into VendorEmployee values(1,4,3,5,4,4) insert into VendorEmployee values(2,4,1,5,5,5) insert into VendorEmployee values(3,4,3,5,4,4) insert into VendorEmployee values(4,4,2,5,4,4) insert into VendorEmployee values(5,5,1,5,5,5) select * from VendorEmployee /* VendorID Emp1orders Emp2Orders Emp3Orders Emp4Orders Emp5Orders ----------- ----------- ----------- ----------- ----------- ----------- 1 4 3 5 4 4 2 4 1 5 5 5 3 4 3 5 4 4 4 4 2 5 4 4 5 5 1 5 5 5 (5 行受影响) */
UNPIVOT转换
select * from ( select * from VendorEmployee )p unpivot ( Orfder for Employee in (Emp1orders,Emp2Orders,Emp3Orders,Emp4Orders,Emp5Orders) )s /* VendorID Orfder Employee ----------- ----------- -------------------------------------------------------------------------------------------------------------------------------- 1 4 Emp1orders 1 3 Emp2Orders 1 5 Emp3Orders 1 4 Emp4Orders 1 4 Emp5Orders 2 4 Emp1orders 2 1 Emp2Orders 2 5 Emp3Orders 2 5 Emp4Orders 2 5 Emp5Orders 3 4 Emp1orders 3 3 Emp2Orders 3 5 Emp3Orders 3 4 Emp4Orders 3 4 Emp5Orders 4 4 Emp1orders 4 2 Emp2Orders 4 5 Emp3Orders 4 4 Emp4Orders 4 4 Emp5Orders 5 5 Emp1orders 5 1 Emp2Orders 5 5 Emp3Orders 5 5 Emp4Orders 5 5 Emp5Orders (25 行受影响) */
--把上面的表再复制到别的表上去然后再pivot下旋转下看看
--如下
select * into ##aa from ( select * from ( select * from VendorEmployee )p unpivot ( Orfder for Employee in (Emp1orders,Emp2Orders,Emp3Orders,Emp4Orders,Emp5Orders) )s )f
--执行旋转。povit
select * from ( select * from ##aa )p pivot ( sum(Orfder) for Employee in (Emp1orders,Emp2Orders,Emp3Orders,Emp4Orders,Emp5Orders) )f order by vendorID /* VendorID Emp1orders Emp2Orders Emp3Orders Emp4Orders Emp5Orders ----------- ----------- ----------- ----------- ----------- ----------- 1 4 3 5 4 4 2 4 1 5 5 5 3 4 3 5 4 4 4 4 2 5 4 4 5 5 1 5 5 5 (5 行受影响) */ -- 很简单的两个旋转来旋转去的。
*作者：Stephenzhou(阿蒙)
*日期: 2012.12.3
*Mail:[email protected]
*另外：转载请著名出处。
*博客地址：http://blog.csdn.net/szstephenzhou