oracle 分析函数 FIRST_VALUE、LAST_VALUE

用SCOTT/TIGER登录。

FIRST_VALUE、LAST_VALUE是两个分析函数。返回结果集中排在第一位和最后一位的值。

使用FIRST_VALUE：

SELECT DEPTNO, JOB, SUM(SAL), FIRST_VALUE(SUM(SAL)) OVER (PARTITION BY DEPTNO ORDER BY SUM(SAL)) 
FROM EMP GROUP BY DEPTNO, JOB ORDER BY DEPTNO, JOB;

结果：

使用LAST_VALUE：

SELECT DEPTNO, JOB, SUM(SAL), LAST_VALUE(SUM(SAL)) OVER (PARTITION BY DEPTNO ORDER BY SUM(SAL) ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) 
FROM EMP GROUP BY DEPTNO, JOB ORDER BY DEPTNO, JOB;

结果：

对于LAST_VALUE，要加

ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING

否则，SQL如：

SELECT DEPTNO, JOB, SUM(SAL), LAST_VALUE(SUM(SAL)) OVER (PARTITION BY DEPTNO ORDER BY SUM(SAL)) 
FROM EMP GROUP BY DEPTNO, JOB ORDER BY DEPTNO, JOB;

结果：

就不对了。