Oracle 12C -- top-n查询新特性

Oracle 12C -- top-n查询新特性
在12C中，增加了一些新的特性。可以指定返回结果集的指定数量的行、或按照百分比返回行。

SQL> select count(*) from emp;

  COUNT(*)
----------
        14

SQL> select empno,hiredate from emp order by hiredate;

     EMPNO HIREDATE
---------- ---------
      7369 17-DEC-80
      7499 20-FEB-81
      7521 22-FEB-81
      7566 02-APR-81
      7698 01-MAY-81
      7782 09-JUN-81
      7844 08-SEP-81
      7654 28-SEP-81
      7839 17-NOV-81
      7900 03-DEC-81
      7902 03-DEC-81

     EMPNO HIREDATE
---------- ---------
      7934 23-JAN-82
      7788 19-APR-87
      7876 23-MAY-87

14 rows selected.
SQL> select empno,hiredate from emp order by hiredate offset 8 rows;

     EMPNO HIREDATE
---------- ---------
      7839 17-NOV-81
      7900 03-DEC-81
      7902 03-DEC-81
      7934 23-JAN-82
      7788 19-APR-87
      7876 23-MAY-87

6 rows selected.
SQL> select empno,hiredate from emp order by hiredate fetch first 25 percent rows only;

     EMPNO HIREDATE
---------- ---------
      7369 17-DEC-80
      7499 20-FEB-81
      7521 22-FEB-81
      7566 02-APR-81

SQL>