层次查询 select * from emp; select empno, ename, job, mgr, sal, deptno,level lv, sys_connect_by_path(ename, '->') tree_path, connect_by_root(ename) tree_root, connect_by_isleaf isleaf, decode(connect_by_isleaf,1,ename,null) tree_leaf from emp start with…

Oracle “CONNECT BY”是层次查询子句,一般用于树状或者层次结果集的查询.其语法是: 1 [ START WITH condition ]2 CONNECT BY [ NOCYCLE ] conditionThe start with .. connect by clause can be used to select data that has a hierarchical relationship (usually some sort of parent->child (bos…

Oracle “CONNECT BY” 使用 功能说明: 语法结构如下: [ START WITH condition ] CONNECT BY [ NOCYCLE ] condition 说明: 1. START WITH:告诉系统以哪个节点作为根结点开始查找并构造结果集,该节点即为返回记录中的最高节点. 2. 当分层查询中存在上下层互为父子节点的情况时,会返回ORA-01436错误.此时,需要在connect by后面加上NOCYCLE关键字.同时,可用connect_by_iscycle伪…

Oracle “CONNECT BY”是层次查询子句,一般用于树状或者层次结果集的查询.其语法是: ? 1 2 [ START WITH condition ] CONNECT BY [ NOCYCLE ] condition The start with .. connect by clause can be used to select data that has a hierarchical relationship (usually some sort of parent->child…

Oracle “CONNECT BY”是层次查询子句,一般用于树状或者层次结果集的查询.其语法是: [ START WITH condition ] CONNECT BY [ NOCYCLE ] condition 说明: 1. START WITH:告诉系统以哪个节点作为根结点开始查找并构造结果集,该节点即为返回记录中的最高节点. 2. 当分层查询中存在上下层互为父子节点的情况时,会返回ORA-01436错误.此时,需要在connect by后面加上NOCYCLE关键字.同时,可用connec…

递归: select *    from t_pams_solution t   start with t.id is null  connect by prior id = t.parent_id   order by level desc 红字部分分别为 表名,开始条件,子节点与根关联条件 反递归: select rownum num,         level lev,         connect_by_root(id) id,         connect_by_root(sol…

SELECT * from CONNECT BY {PRIOR列名1=列名2|列名1=PRIOR列名2} [START WITH]; Oracle的递归查询:     START WITH :描述开始查询的节点,根节点.     CONNECT BY PRIOR:描述节点的之间的关系,PRIOR运算符在一侧表示父节点,在另一侧表示子节点.…

查找员工编号为7369的领导: 1 SELECT LEVEL,E.* FROM EMP E CONNECT BY PRIOR E.MGR = E.EMPNO START WITH E.EMPNO = 78762 ORDER BY LEVEL DESC "start with" -- this identifies all LEVEL=1 nodes in the tree "connect by" -- describes how to walk from the…

先用scott用户下的emp表做实验.emp表有个字段,一个是empno(员工编号),另一个是mgr(上级经理编号)下面是表中所有数据 1 select * from emp start with empno=7698 connect by  mgr=prior empno; 执行结果如下: 得到的结果是empno=7698的数据,以及会得到mgr=7698的数据.它是向下递归的, 即我们从empno=7698开始遍历,去找出mgr=7698的所有数据S(用S代表查出的所有数据.), 然后在从S…

今天偶然看到connect by,但记不太清楚具体用法了.转了个博客(写的蛮好的),当作笔记. http://www.cnblogs.com/linjiqin/p/3152690.html 先用scott用户下的emp表做实验. emp表有个字段,一个是empno(员工编号),另一个是mgr(上级经理编号)下面是表中所有数据 1 select * from emp start with empno=7698 connect by  mgr=prior empno; 执行结果如下: 得到的结果是e…