清-华-园

摘要： (1)使用用rowid方法 查询重复数据:select * from person a where rowid !=(select max(rowid) from person b where a.cardid=b.cardid and a.pname=b.pname); 删除重复数据:delete 阅读全文

摘要： ①select * from (select employee.*, rownum r from employee) where r between 2 and 5; ②select * from (select employee.*, rownum r from employee where ro 阅读全文