How to get result from parent child table

Question

Work on SQL-Server. My table structure is below

CREATE TABLE [dbo].[AgentInfo](
    [AgentID] [int] NOT NULL,
    [ParentID] [int] NULL,
 CONST         


        

Answer 1

Try something like this:

WITH Merged (AgentId, ParentId) AS (
     SELECT AgentId, ParentId FROM AgentInfo WHERE ParentId = -1
     UNION ALL
     SELECT AgentInfo.AgentId, AgentInfo.ParentId FROM AgentInfo INNER JOIN Merged ON AgentInfo.AgentId = Merged.ParentId
)
SELECT * FROM Merged