时间:2021-07-01 10:21:17 帮助过:22人阅读
- 1 -- 表结构
- 2 create table menu(
- 3 id varchar2(64) not null,
- 4 parent_id varchar2(64) not null,
- 5 name varchar2(100) not null,
- 6 depth number(2) not null,
- 7 primary key (id)
- 8 )
- 9
- 10 -- 初始化数据
- 11 -- 顶级菜单
- 12 insert into menu values (‘100000‘, ‘0‘, ‘顶级菜单1‘, 1);
- 13 insert into menu values (‘200000‘, ‘0‘, ‘顶级菜单2‘, 1);
- 14 insert into menu values (‘300000‘, ‘0‘, ‘顶级菜单3‘, 1);
- 15
- 16 -- 父级菜单
- 17 -- 顶级菜单1 直接子菜单
- 18 insert into menu values (‘110000‘, ‘100000‘, ‘菜单11‘, 2);
- 19 insert into menu values (‘120000‘, ‘100000‘, ‘菜单12‘, 2);
- 20 insert into menu values (‘130000‘, ‘100000‘, ‘菜单13‘, 2);
- 21 insert into menu values (‘140000‘, ‘100000‘, ‘菜单14‘, 2);
- 22 -- 顶级菜单2 直接子菜单
- 23 insert into menu values (‘210000‘, ‘200000‘, ‘菜单21‘, 2);
- 24 insert into menu values (‘220000‘, ‘200000‘, ‘菜单22‘, 2);
- 25 insert into menu values (‘230000‘, ‘200000‘, ‘菜单23‘, 2);
- 26 -- 顶级菜单3 直接子菜单
- 27 insert into menu values (‘310000‘, ‘300000‘, ‘菜单31‘, 2);
- 28
- 29 -- 菜单13 直接子菜单
- 30 insert into menu values (‘131000‘, ‘130000‘, ‘菜单131‘, 3);
- 31 insert into menu values (‘132000‘, ‘130000‘, ‘菜单132‘, 3);
- 32 insert into menu values (‘133000‘, ‘130000‘, ‘菜单133‘, 3);
- 33
- 34 -- 菜单132 直接子菜单
- 35 insert into menu values (‘132100‘, ‘132000‘, ‘菜单1321‘, 4);
- 36 insert into menu values (‘132200‘, ‘132000‘, ‘菜单1332‘, 4);
- 37
生成的菜单层次结构如下:
顶级菜单1
菜单11
菜单12
菜单13
菜单131
菜单132
菜单1321
菜单1322
菜单133
菜单14
顶级菜单2
菜单21
菜单22
菜单23
顶级菜单3
菜单31
2、SQL查询
- --prior放的左右位置决定了检索是自底向上还是自顶向下. 左边是自上而下(找子节点),右边是自下而上(找父节点)
- --找父节点
- select * from menu start with id=‘130000‘ connect by id = prior parent_id;
- --找子节点节点
- -- (子节点)id为130000的菜单,以及130000菜单下的所有直接或间接子菜单(prior 在左边, prior、parent_id(等号右边)在右边)
- select * from menu start with id=‘130000‘ connect by prior id = parent_id ;
- -- (父节点)id为1321的菜单,以及1321菜单下的所有直接或间接父菜单(prior、parent_id(等号左边) 都在左边)
- select * from menu start with id=‘132100‘ connect by prior parent_id = id;
- -- prior 后面跟的是(parent_id) 则是查找父节点,prior后面跟的是(id)则是查找子节点
- --根据菜单组分类统计每个菜单包含子菜单的个数
- select id, max(name) name, count(1) from menu
- group by id
- connect by prior parent_id = id
- order by id
- -- 查询所有的叶子节点
- select t2.* from menu t2 where id not in(select t.parent_id from menu t) order by id;
三、性能问题
对于 start with connect by语句的执行,oracle会进行递归查询,当数据量大的时候会产生性能相关问题。
- --生成执行计划
- explain plan for select * from menu start with id=‘132100‘ connect by prior parent_id = id;
- -- 查询执行计划
- select * from table( dbms_xplan.display);
语句执行计划结果如下:
- Plan hash value: 3563250490
- ----------------------------------------------------------------------------------------------
- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
- ----------------------------------------------------------------------------------------------
- | 0 | SELECT STATEMENT | | 1 | 133 | 1 (0)| 00:00:01 |
- |* 1 | CONNECT BY WITH FILTERING | | | | | |
- | 2 | TABLE ACCESS BY INDEX ROWID | MENU | 1 | 133 | 1 (0)| 00:00:01 |
- |* 3 | INDEX UNIQUE SCAN | SYS_C0018586 | 1 | | 1 (0)| 00:00:01 |
- | 4 | NESTED LOOPS | | | | | |
- | 5 | CONNECT BY PUMP | | | | | |
- | 6 | TABLE ACCESS BY INDEX ROWID| MENU | 1 | 133 | 1 (0)| 00:00:01 |
- |* 7 | INDEX UNIQUE SCAN | SYS_C0018586 | 1 | | 1 (0)| 00:00:01 |
- ----------------------------------------------------------------------------------------------
- Predicate Information (identified by operation id):
- ---------------------------------------------------
- 1 - access("ID"=PRIOR "PARENT_ID")
- 3 - access("ID"=‘132100‘)
- 7 - access("ID"=PRIOR "PARENT_ID")
- Note
- -----
- - dynamic sampling used for this statement
[转载]oracle树形查询 start with connect by
标签:复制 for order isp 生成 with 间接 use menu