Oracle有关树的查询

1，查询所有节点

select * from busi_jgrs  start with id = '1' connect by prior id = pid;

start with id = '1'

意思是以id为1开始。

2，查询末节点

select *  from busi_jgrs where id in (select id                from (select id, CONNECT_BY_ISLEAF isleaf                        from busi_jgrs                       start with id = '1'                      connect by prior id = pid) tt               where tt.isleaf = 1)

3，查询某等级的节点。（比如等级为3）

select t.*, level, CONNECT_BY_ISLEAF isleaf  from tree t where level = 3 start with tid = '1'connect by prior tid = pid

4，查询：某等级且为底层节点。（比如等级为2）

select t.*, level, CONNECT_BY_ISLEAF isleaf  from tree t where level = 2   and CONNECT_BY_ISLEAF = 1 start with tid = '1'connect by prior tid = pid;

level是Oracle本有的字段类似于rowid