ORACLE是ORACLE公司的数据产品，支持海量数据存储，支持分布式布暑，支持多用户，跨平台，数据安全完整性控制性能优越，是一个OR
1、对数据库SQL2005、Oracle熟悉吗？
SQL2005是微软公司的数据库产品。是一个RDBMS数据库，一般应用在一些中型数据库的应用，不能跨平台。
ORACLE是ORACLE公司的数据产品，支持海量数据存储，支持分布式布暑，支持多用户，，跨平台，数据安全完整性控制性能优越，是一个ORDBMS，一般用在大型公司。
2、能不能设计数据库？如何实现数据库导入与导出的更新 使用POWERDISINE工具的使用，一般满足第三范式就可以了。EXP与IMP数据库的逻辑导入与导出
3、如何只显示重复数据，或不显示重复数据
显示重复：
select * from tablename group by id having count(*)>1
不显示重复：
select * from tablename group by id having count(*)=1
4、什么是数据库的映射
就是将数据库的表与字段对应到模型层类名与属性的过程
5、写分页有哪些方法，你一般用什么方法？用SQL语句写一个分页？
如何用存储过程写分页？
在SQLSERVER中使用TOP分页，在ORACLE中用ROWNUM，或分析函数ROW_NUMBER 使用TOP： select top 20,n.* from tablename n minus select top 10,m.* from tablename m
使用分析函数：
select * from (select n.*,row_number() over(order by columnname) num from tablename n) where num>=10 and num <=20;
使用过程时，只要将分页的范围用两个参数就可以实现。在ORACLE中，要将过程封装在包里，还要用动态游标变量才能实现数据集的返回。
6、ORACLE中左连接与右连接
左连接：LEFT JOIN 右连接：RIGHT JOIN
select n.column,m.column from tablename1 n left join tablename2 m on n.columnname=m.columnname
用WHERE实现：
select n.column,m.column from tablename1 n， tablename2 m where n.columnname( )=m.columnname
7、什么是反射、序列化、反序列化？事务有几种级别？
反射是在程序运行时动态访问DDL的一种方式。序列化是将对象对二进制、XML等方式直接向文件的存储。反序列化是将存储到文件的对象取出的过程。事务的级别的三种：页面级、应用程序级、数据库级。
【专题推荐】：2020年oracle面试题汇总（最新）
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