oracle first_value，last_valus

示例1：

SELECT first_value(comm ) over() firstval,
       last_value(comm ) over() lastval,
       e.*
  FROM emp e

结果：

示例2：

SELECT first_value(comm ) over(partition by deptno) firstval,
       last_value(comm ) over(partition by deptno) lastval,
       e.*
  FROM emp e

结果：

示例3：

SELECT first_value(comm ) over(partition by deptno order by sal) firstval,
       last_value(comm ) over(partition by deptno order by sal) lastval,
       e.*
  FROM emp e

结果：

示例4：

SELECT first_value(comm ignore nulls) over(partition by deptno order by sal) firstval,
       last_value(comm ignore nulls) over(partition by deptno order by sal) lastval,
       e.*
  FROM emp e

结果：

示例5：

SELECT first_value(sal ignore nulls) over(partition by deptno order by sal) firstval,
       last_value(sal ignore nulls) over(partition by deptno order by sal) lastval,
       e.*
  FROM emp e;

SELECT first_value(sal ignore nulls) over(partition by deptno order by sal) firstval,
       last_value(sal ignore nulls) over(partition by deptno order by sal ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING ) lastval,
       e.*
  FROM emp e

结果：

第一个sql结果：

第二个sql结果：

oracle first_value，last_valus

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