Oracle取TOP N条记录

在SQL Server里面有top关键字可以很方便的取出前N条记录，但是Oracle里面却没有top的使用，类似实现取出前N条记录的简单方法如下：

方法1：利用ROW_NUMBER函数

取出前5条记录：

SELECT NO FROM (

    SELECT ROW_NUMBER() OVER (ORDER BY NO) RNO, NO FROM ROWNUM_TEST

)WHERE RNO <= 5  ORDER BY NO ;

取出中间5条记录：

SELECT NO FROM (

    SELECT ROW_NUMBER() OVER (ORDER BY NO) RNO, NO FROM ROWNUM_TEST

) WHERE RNO BETWEEN 5 AND 10 ORDER BY NO;

 

方法2：利用子查询

取出前5条记录：

SELECT NO FROM (

    SELECT NO FROM ROWNUM_TEST  ORDER BY NO

)WHERE ROWNUM <= 5  ORDER BY NO ;

取出中间5条记录：

SELECT NO  FROM (

    SELECT NO, ROWNUM RNO FROM (

        SELECT NO FROM ROWNUM_TEST  ORDER BY NO

    )

) WHERE RNO BETWEEN 5 AND 10  ORDER BY NO;