ORACLE中树操作递归算法connect by prior

创建表 linshi_ljq

在其中插入数据

--父菜单

insert into linshi_ljq(value, value_meaning, parent_value_low) values(1, '父菜单1',null);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(2, '父菜单2',null);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(3, '父菜单3',null);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(4, '父菜单4',null);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(5, '父菜单5',null);

--一级菜单

insert into linshi_ljq(value, value_meaning, parent_value_low) values(6, '一级菜单6',1);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(7, '一级菜单7',1);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(8, '一级菜单8',1);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(9, '一级菜单9',2);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(10, '一级菜单10',2);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(11, '一级菜单11',2);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(12, '一级菜单12',3);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(13, '一级菜单13',3);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(14, '一级菜单14',3);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(15, '一级菜单15',4);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(16, '一级菜单16',4);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(17, '一级菜单17',4);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(18, '一级菜单18',5);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(19, '一级菜单19',5);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(20, '一级菜单20',5);

--二级菜单

insert into linshi_ljq(value, value_meaning, parent_value_low) values(21, '二级菜单21',6);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(22, '二级菜单22',6);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(23, '二级菜单23',7);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(24, '二级菜单24',7);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(25, '二级菜单25',8);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(26, '二级菜单26',9);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(27, '二级菜单27',10);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(28, '二级菜单28',11);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(29, '二级菜单29',12);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(30, '二级菜单30',13);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(31, '二级菜单31',14);

insert into linshi_ljq(value
4000
, value_meaning, parent_value_low) values(32, '二级菜单32',15);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(33, '二级菜单33',16);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(34, '二级菜单34',17);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(35, '二级菜单35',18);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(36, '二级菜单36',19);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(37, '二级菜单37',20);

--三级菜单

insert into linshi_ljq(value, value_meaning, parent_value_low) values(38, '三级菜单38',21);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(39, '三级菜单39',22);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(40, '三级菜单40',23);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(41, '三级菜单41',24);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(42, '三级菜单42',25);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(43, '三级菜单43',26);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(44, '三级菜单44',27);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(45, '三级菜单45',28);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(46, '三级菜单46',28);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(47, '三级菜单47',29);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(48, '三级菜单48',30);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(49, '三级菜单49',31);

insert into linshi_ljq(value, value_meaning, parent_value_low) values(50, '三级菜单50',31);

commit;

一、基本语法

select ... from <TableName>

where 条件1

start with 条件2

connect by prior  条件3

例如：select *

  from linshi_ljq t

 start with t.parent_value_low = '0'

connect by prior t.value = t.parent_value_low;

解析：prior表示上一条记录。比如说 connect by prior t.value = t.parent_value_low 就是说上一条记录的value值等于这条记录的parent_value_low的值，即本条记录的父亲是上一条记录。

prior运算符在父节点一侧还是在子节点一侧，决定了查找数结构的顺序是自定向下还是自底向上。

prior在子节点一侧表示自定向下，查询出的是所有的子类结果：

select *

  from linshi_ljq t

 start with t.parent_value_low = '0'

connect by prior t.value = t.parent_value_low;

prior 在父节点一侧表示自底向上，查询出的是所有的父类结果：

select *

  from linshi_ljq t

 start with t.parent_value_low = '2'

connect by prior t.parent_value_low = t.value

二、关键字

1）level 表示层级

例如：

select a.value,a.value_meaning,level

  from linshi_ljq a

 start with a.parent_value_low = '0'

connect by prior a.value = a.parent_value_low;



2) 列出全部的路径：SYS_CONNECT_BY_PATH

例如:select sys_connect_by_path(t.value_meaning, '/')

  from linshi_ljq t

  where t.value='50'

 start with t.parent_value_low = '0'

connect by prior t.value = t.parent_value_low;



3)判断当前节点是否是叶子节点，如果是显示1，如果不是显示0：CONNECT_BY_ISLEAF

例如：

select connect_by_isleaf,b.*

  from linshi_ljq b

 start with b.parent_value_low = '0'

connect by prior b.value = b.parent_value_low



4）返回当前节点的根节点：CONNECT_BY_ROOT

例如：

select connect_by_root value_meaning, b.*

  from linshi_ljq b

 start with b.parent_value_low = '0'

connect by prior b.value = b.parent_value_low