oracle中进行简单树查询(递归查询) ，PRIOR、CONNECT_BY_ROOT的使用

select AD_DEPARTMENT_CODE, AD_DEPARTMENT_UP_LEVEL, AD_DEPARTMENT_NAME   from (select AD_DEPARTMENT_CODE,                AD_DEPARTMENT_UP_LEVEL,                AD_DEPARTMENT_NAME           from AD_DEPT_ARCHITECTURE          order by AD_DEPARTMENT_UP_LEVEL, AD_DEPARTMENT_CODE)  start with AD_DEPARTMENT_CODE = '0' connect by prior AD_DEPARTMENT_CODE = AD_DEPARTMENT_UP_LEVEL; 对from 后边 的select 结果集合进行了排序，然后，start with 、connect by prior这些语句起了作用，按照刚才查询出来结果集的顺序， （1）       先找到AD_DEPARTMENT_CODE = '0'的作为第一条记录(A)，将其加入到要构建的树状结构中。 （2）       然后顺序从排完序的结果集中找出，第一条记录的头一个子结点(B)添加到树中。如第一个子结点还有它的子结点，就依次从刚才的查询出来的结果集中找到B的子节点C1、C2、C3。。。依次添加到树中。 （3）       。。。。  有了from 后的select结果集的排序，得到的树状结构更加有序。

生成媒体频道栏目父子关系树状关系 SELECT APR_CODE, APR_CODE_UP, NAMES   FROM (SELECT A.MEDIA_CODE || '|' || A.CHANNEL_CODE || '|' || A.COLUMN_CODE AS APR_CODE,                A.MEDIA_CODE_UP || '|' || A.CHANNEL_CODE_UP || '|' ||                A.COLUMN_CODE_UP AS APR_CODE_UP,                DECODE((B.MEDIA_NAME || '-' || C.CHANNEL_CODE || '-' ||                       D.COLUMN_NAME),                       '--',                       '产品关系',                       (B.MEDIA_NAME || '|' || C.CHANNEL_CODE || '|' ||                       D.COLUMN_NAME)) NAMES           FROM COLUMNS D, CHANNEL C, MEDIA B, AD_PRODUCT_RELATION A          WHERE A.MEDIA_CODE = B.MEDIA_CODE(+)            AND A.MEDIA_CODE = C.MEDIA_CODE(+)            AND A.CHANNEL_CODE = C.CHANNEL_CODE(+)            AND A.MEDIA_CODE = D.MEDIA_CODE(+)            AND A.CHANNEL_CODE = D.CHANNEL_CODE(+)            AND A.COLUMN_CODE = D.COLUMN_CODE(+))  START WITH APR_CODE = '0|0|0' CONNECT BY PRIOR APR_CODE = APR_CODE_UP   这里利用'-' 和'|'来进行区分，找出了树状结构的根 为了构建树， （1）先建立了树结构的根，字段这里都设为“0”或者“00” （2）然后再根据需要填充数据 （3）利用上边的oracle的 PRIOR，CONNECT_BY_ROOT 等进行层次查询

递归查询时：由于数据类型不正确而导致 “ ORA-01436 : CONNECT BY loop in user data ” 错误原因：在数据库表TRASFER中，TRASFER字段为number类型，而TAPE_NO字段为Varchar2类型。由于在进行父子关系判定中“TRANSFER = TAPE_NO”两者的字段类型不同而导致：ORA-01436   正确语句： SELECT TRANSFER, TAPE_NO, TRANSFER_NAME   FROM (SELECT TRANSFER, TAPE_NO, TRANSFER_NAME           FROM TRANSFER          ORDER BY TAPE_NO, TRANSFER)  START WITH TRANSFER = 0 CONNECT BY PRIOR TO_CHAR(TRANSFER) = TAPE_NO

 

 

参考一

PL/SQL基础：阶层查询 作者：itpub cxck   2007-05-08 内容导航：  ORACLE 10g 新增了阶层查询操作符PRIOR，CONNECT_BY_ROOT ■PRIOR 阶层查询的CONNECY BY condition的条件式需要用到PRIOR来指定父节点， 作为运算符，PRIOR和加(+)减(-)运算的优先级相同。 ■阶层查询 语法：START WITH condition CONNECT BY NOCYCLE condition START WITH 指定阶层的根 CONNECT BY 指定阶层的父/子关系 NOCYCLE 存在CONNECT BY LOOP的纪录时，也返回查询结果。 condition ... PRIOR expr = expr 或者 ... expr = PRIOR expr 例： CONNECT BY last_name != 'King' AND PRIOR employee_id = manager_id ... CONNECT BY PRIOR employee_id = manager_id and PRIOR account_mgr_id = customer_id ... ■CONNECT_BY_ROOT 查询指定根的阶层数据。 ■CONNECT BY子句的例子 通过CONNECT BY子句定义职员和上司的关系。 SQL>SELECT employee_id, last_name, manager_id FROM employees CONNECT BY PRIOR employee_id = manager_id; EMPLOYEE_ID LAST_NAME MANAGER_ID ----------- ------------------------- ---------- 101 Kochhar 100 108 Greenberg 101 109 Faviet 108 110 Chen 108 111 Sciarra 108 112 Urman 108 113 Popp 108 200 Whalen 101 ■LEVEL的例子 通过LEVEL虚拟列表示节点的关系。 SQL>SELECT employee_id, last_name, manager_id, LEVEL FROM employees CONNECT BY PRIOR employee_id = manager_id; EMPLOYEE_ID LAST_NAME MANAGER_ID LEVEL ----------- ------------------------- ---------- ---------- 101 Kochhar 100 1 108 Greenberg 101 2 109 Faviet 108 3 110 Chen 108 3 111 Sciarra 108 3 112 Urman 108 3 113 Popp 108 3 ■START WITH子句的例子 通过START WITH指定根节点，ORDER SIBLINGS BY保持阶层的顺序。 SQL>SELECT last_name, employee_id, manager_id, LEVEL FROM employees START WITH employee_id = 100 CONNECT BY PRIOR employee_id = manager_id ORDER SIBLINGS BY last_name; LAST_NAME EMPLOYEE_ID MANAGER_ID LEVEL ------------------------- ----------- ---------- ---------- King 100 1 Cambrault 148 100 2 Bates 172 148 3 Bloom 169 148 3 Fox 170 148 3 Kumar 173 148 3 Ozer 168 148 3 Smith 171 148 3 De Haan 102 100 2 Hunold 103 102 3 Austin 105 103 4 Ernst 104 103 4 Lorentz 107 103 4 Pataballa 106 103 4 Errazuriz 147 100 2 Ande 166 147 3 Banda 167 147 3   hr.employees里，Steven King是公司的最高责任者，没有上司，他有一个叫John Russell的下属是部门80的管理者。 更新employees表，把Russell设置成King的上司，这样就产生了CONNECT BY LOOP。 SQL>UPDATE employees SET manager_id = 145 WHERE employee_id = 100; SQL>SELECT last_name "Employee", LEVEL, SYS_CONNECT_BY_PATH(last_name, '/') "Path" FROM employees WHERE level <= 3 AND department_id = 80 START WITH last_name = 'King' CONNECT BY PRIOR employee_id = manager_id AND LEVEL <= 4; 2 3 4 5 6 7 ERROR: ORA-01436: CONNECT BY loop in user data CONNECT BY NOCYCLE强制返回查询结果。CONNECT_BY_ISCYCLE显示是否存在LOOP。 SQL>SELECT last_name "Employee", CONNECT_BY_ISCYCLE "Cycle", LEVEL, SYS_CONNECT_BY_PATH(last_name, '/') "Path" FROM employees WHERE level <= 3 AND department_id = 80 START WITH last_name = 'King' CONNECT BY NOCYCLE PRIOR employee_id = manager_id AND LEVEL <= 4; Employee Cycle LEVEL Path ------------------------- ------ ------ ------------------------- Russell 1 2 /King/Russell Tucker 0 3 /King/Russell/Tucker Bernstein 0 3 /King/Russell/Bernstein Hall 0 3 /King/Russell/Hall Olsen 0 3 /King/Russell/Olsen Cambrault 0 3 /King/Russell/Cambrault Tuvault 0 3 /King/Russell/Tuvault Partners 0 2 /King/Partners King 0 3 /King/Partners/King Sully 0 3 /King/Partners/Sully McEwen 0 3 /King/Partners/McEwen   ■CONNECT_BY_ROOT的例子 1，查询110部门的职员，上司，职员和上司之间级别差及路径。 SELECT last_name "Employee", CONNECT_BY_ROOT last_name "Manager", LEVEL-1 "Pathlen", SYS_CONNECT_BY_PATH(last_name, '/') "Path" FROM employees WHERE LEVEL > 1 and department_id = 110 CONNECT BY PRIOR employee_id = manager_id; Employee Manager Pathlen Path --------------- ------------ ---------- ----------------------------------- Higgins Kochhar 1 /Kochhar/Higgins Gietz Kochhar 2 /Kochhar/Higgins/Gietz Gietz Higgins 1 /Higgins/Gietz Higgins King 2 /King/Kochhar/Higgins Gietz King 3 /King/Kochhar/Higgins/Gietz   2，使用GROUP BY语句，查询110部门的职员以及该职员下属职员的工资和。 SELECT name, SUM(salary) "Total_Salary" FROM ( SELECT CONNECT_BY_ROOT last_name as name, Salary FROM employees WHERE department_id = 110 CONNECT BY PRIOR employee_id = manager_id) GROUP BY name; NAME Total_Salary ------------------------- ------------ Gietz 8300 Higgins 20300 King 20300 Kochhar 20300   1

 

参考二

对于oracle进行简单树查询(递归查询) DEPTID PAREDEPTID NAME NUMBER NUMBER CHAR (40 Byte) 部门id 父部门id(所属部门id) 部门名称   通过子节点向根节点追朔. select * from persons.dept start with deptid=76 connect by prior paredeptid=deptid 通过根节点遍历子节点. select * from persons.dept start with paredeptid=0 connect by prior deptid=paredeptid 可通过level 关键字查询所在层次. select a.*,level from persons.dept a start with paredeptid=0 connect by prior deptid=paredeptid 再次复习一下:start with ...connect by 的用法， start with 后面所跟的就是就是递归的种子。 递归的种子也就是递归开始的地方 connect by 后面的"prior" 如果缺省：则只能查询到符合条件的起始行，并不进行递归查询； connect by prior 后面所放的字段是有关系的，它指明了查询的方向。 对于prior，我是这样理解的： 上边例子中，比如：“prior deptid = paredeptid”，意思是：祖先（上一层记录）的deptid等于本条记录的paredeptid，即：通过根节点遍历子节点 练习： 通过子节点获得顶节点 select FIRST_VALUE(deptid)   OVER (ORDER BY LEVEL DESC ROWS UNBOUNDED PRECEDING) AS firstdeptid from  persons.dept   start with deptid=76 connect by prior paredeptid=deptid