删除数据表重复记录，并保留最小rowid

• 例如有一张表city，表内容如下

create table CITY
(
	cityno   NUMBER(2),
	cityname VARCHAR2(14)
)

• 查询包含 rowid 结果如下：

SELECT a.*, a.rowid FROM city a

• 查询需要删除的重复的记录，并保留最小的rowid

SELECT a.*, a.rowid
  FROM city a
 WHERE a.rowid IN (SELECT max(rowid)
                     FROM city t2
                    WHERE 1 = 1
                    GROUP BY t2.cityname
                   HAVING COUNT(cityname) > 1)

• 删除

DELETE
  FROM city a
 WHERE a.rowid IN (SELECT max(rowid)
                     FROM city t2
                    WHERE 1 = 1
                    GROUP BY t2.cityname
                   HAVING COUNT(cityname) > 1)

删除数据表重复记录，并保留最小rowid

原文：https://www.cnblogs.com/sheldonxiun/p/13362372.html