pgsql删除重复记录

如下：

DELETE 
FROM
    categories a 
WHERE
    ( a.id, a.name, a.parent_id ) IN ( SELECT id, name, parent_id FROM categories GROUP BY id, name, parent_id HAVING count( * ) > 1 ) 
    AND ctid NOT IN ( SELECT min(ctid) FROM categories GROUP BY id, name, parent_id HAVING count( * ) > 1 )

关键点：oracle中有内部id为rowid, 在postgresql中有ctid.

参照：oracle rowid and postgresql ctid

参照：SQL 删除重复记录，并保留其中一条