mysql - POSTGRE how to select parent name from hierarchical table -


how select hierarchical table parent id? have table this

+-----------+------------+-------------+ | id        | parent_id  | name        | +-----------+------------+-------------+ |1          | 0          |           | +-----------+------------+-------------+ |2          | 1          | a1          | +-----------+------------+-------------+ |3          | 0          | b           | +-----------+------------+-------------+ |4          | 3          | b1          | +-----------+------------+-------------+ |5          | 3          | b2          | +-----------+------------+-------------+

and want show table this

+-----------+------------+-------------+ | id        | name       | parent      | +-----------+------------+-------------+ |1          |          | null        | +-----------+------------+-------------+ |2          | a1         |           | +-----------+------------+-------------+ |3          | b          | null        | +-----------+------------+-------------+ |4          | b1         | b           | +-----------+------------+-------------+ |5          | b2         | b           | +-----------+------------+-------------+

is possible create select this? know how create in postgre or mysql, please give me suggest,

simply use left join:

select t1.id, t1.name, t2.name parent yourtable t1 left join yourtable t2 on t1.parent_id = t2.id order t1.id

demo here


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