Using sql to implement cascade query in ORACLE database
select *
// field to query
from table
//table with child contact ID and parent contact ID
start with selfid=id
//Given a startid (the field name is the sub-contact ID, and the starting ID number)
connect by prior selfid=parentid
//The connection condition is that the child joint is equal to the parent joint
Take a chestnut and take a look---------""""""
The db data fields are as follows:
task_id task_name parent_task_id
000001 A 0
000002 A_1 000001
000005 A_2 000001
task_id task_name parent_task_id
000001 A 0
000002 A_1 000001
000005 A_2 000001
check sentence:
select t.task_id ,t.task_name ,t.parent_task_id
from t_task t
start with task_id='000001'
connect by prior task_id = parent_task_id;
from t_task t
start with task_id='000001'
connect by prior task_id = parent_task_id;
The query structure is:
task_id task_name parent_task_id
000001 A 0
000002 A_1 000001
000005 A_2 000001
000001 A 0
000002 A_1 000001
000005 A_2 000001
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