postgreSQL ltree工具獲取上下級

select * from departments

/*
　　查詢子級部門  path <@ ''   查詢上級部門  path @>

　　path: 部門id用'.'鏈接
*/
select id,name,path,parent_id from departments where path <@ cast('NE*********Pc.NE*********Pd.NE*********Ra' as ltree)