一个表中重复数据的处理
- 作者: 嗫?暁雲?
- 来源: 51数据库
- 2022-08-17
查询 columnName 有重复的数据，保留 id 最大的一个。 SELECT MAX(id) AS id, columnName, COUNT(columnName ) AS countNumber FROM tableName GROUP BY columnName HAVING countNumber> 1 ORDER BY countNumber DESC; 删除 columnName 有重复的数据，保留 id 最小的一个。 DELETE tableName t1 FROM tableName t1, (SELECT min(id) id , columnName FROM tableName GROUP BY columnName HAVING COUNT(1) > 1 ) t2 WHERE t1.columnName = t2.columnName AND t1. id > t2.id;
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