fairy_xzc 发表于 2013-1-29 15:28:32

ORACLE三层子查询

以Oracle11G数据库中scott用户的emp雇员表为例
 
第一层查询

SELECT EMPNO, ENAMEFROM EMP ORDER BY EMPNO;结果

http://dl.iteye.com/upload/attachment/575241/311031a3-2e3a-3aa9-afbb-67a0ee217a2c.png



第二层查询

SELECT ROWNUM, EMPNO, ENAMEFROM (SELECT EMPNO, ENAME   FROM EMP      ORDER BY EMPNO)WHERE ROWNUM <= 10;结果

http://dl.iteye.com/upload/attachment/575243/b974bd54-370b-3689-b321-5fead808236a.png



第三层查询

SELECT EMPNO, ENAMEFROM (SELECT ROWNUM RN, EMPNO, ENAME   FROM (SELECT EMPNO, ENAME          FROM EMP         ORDER BY EMPNO)   WHERE ROWNUM <= 10)WHERE RN > 5; 结果

http://dl.iteye.com/upload/attachment/575245/dfc18cd8-f635-3452-bbba-d5bd6fc87d27.png
 
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