oracle和postgresql 递归查询父子关系记录语法区别

oracle:

一、数据

db数据字段如下：

task_id             task_name         t.parent_task_id       ***

***                     ***                          ***                               ***

000001            t1                         ***                                 ***

000002            t11                       000001                        ***

000005            t12                       000001                         ***

000003            t111                    000002                         ***

000004            t1111                  000003                         ***

000006            t121                    000005                         ***

000007            t1211                  000006                         ***

***                     ***                       ***                                 ***

二、格式
        Select * from …. Where [结果过滤条件语句]
　　Start with  [and起始条件过滤语句]
　　Connect by prior [and中间记录过滤条件语句]
三、查找所有下级
        select * from tablename start with id=1 connect by prior id=pid
　　注意：此sql能查找id=1的数据的所有下级，写sql语句时要注意，因为是从id开始查找下级，所以connect by prior 子句的条件是         id=pid
四、查找所有上级
       select * from tablename start with id=5 connect by prior pid=id
　　因为是从id开始查找上级，所以connect by prior 子句的条件是pid=d

select t.task_id ,t.task_name ,t.parent_task_id
from t_task t
start with task_id=''
connect by prior task_id = parent_task_id;

五、显示结果

结果显示：

task_id                 task_name          t.parent_task_id

000001                t1          

000002                t11                       000001

000003                t111                     000002

000004                t1111                    000003

000005                t12                       000001

000006                t121                     000005

000007                t1211                   000006

postgresql:

查询父节点下所有的子节点

WITH recursive fileinfo
 (pk_fi_id,
  f_fi_parentid)
AS
(
SELECT
        pk_fi_id ,
        f_fi_parentid
    FROM
        t_fileinfo
    WHERE
        pk_fi_id = '92719f78-22d6-4db1-a484-dff34de76890'
UNION ALL
SELECT
            mm.pk_fi_id ,
            mm.f_fi_parentid
        FROM
            t_fileinfo AS mm
INNER JOIN fileinfo AS child ON mm.f_fi_parentid = child.pk_fi_id
)
SELECT
  *
FROM fileinfo