PostgreSQL如何删除重复值

Question

我在Postgres数据库中有一个表，我忘了插入一个唯一索引。因为那个索引我现在有重复的值。如何删除重复的值？我想在字段translationset_Id和key上添加唯一索引。

Answer 1

我认为你要求这个：

DELETE FROM tablename WHERE id IN (SELECT id FROM (SELECT id, ROW_NUMBER() OVER (partition BY column1, column2, column3 ORDER BY id) AS rnum FROM tablename) t WHERE t.rnum > 1);

Answer 2

您似乎只想删除与translationset_id列相关的重复记录。在这种情况下，我们可以使用Postgres＆＃39;行号功能，用于辨别重复行，然后删除这些重复行。

WITH cte AS
(
    SELECT t.*, ROW_NUMBER() OVER (PARTITION BY translationset_id, key) AS rnum
    FROM yourTable t
)

DELETE FROM yourTable
WHERE translationset_id IN (SELECT translationset_id FROM cte WHERE rnum > 1)

Answer 3

delete from mytable
where exists (select 1
              from mytable t2
              where t2.name = mytable.name and
                    t2.address = mytable.address and
                    t2.zip = mytable.zip and
                    t2.ctid > mytable.ctid
             );

Answer 4

我认为最有效的方法如下。

  DELETE  FROM
    table_name a
    USING table_name b
  WHERE
      a.id < b.id and
      a.same_column = b.same_column;