Lag和Lead函数可以在一次查询中取出同一字段的前N行的数据和后N行的值。这种操作可以使用对相同表的表连接来实现，不过使用LAG和LEAD有更高的效率。

复制代码 代码如下:

CREATE TABLE salaryByMonth

(

employeeNo varchar2(20),

yearMonth varchar2(6),

salary number

) ;

insert into SALARYBYMONTH (EMPLOYEENO, YEARMONTH, SALARY)

values (1, '200805', 500);

insert into SALARYBYMONTH (EMPLOYEENO, YEARMONTH, SALARY)

values (1, '200802', 150);

insert into SALARYBYMONTH (EMPLOYEENO, YEARMONTH, SALARY)

values (1, '200803', 200);

insert into SALARYBYMONTH (EMPLOYEENO, YEARMONTH, SALARY)

values (1, '200804', 300);

insert into SALARYBYMONTH (EMPLOYEENO, YEARMONTH, SALARY)

values (1, '200708', 100);

commit;

SELECT EMPLOYEENO

,YEARMONTH

,SALARY

,MIN(SALARY) KEEP(DENSE_RANK FIRST ORDER BY YEARMONTH) OVER(PARTITION BY EMPLOYEENO) FIRST_SALARY -- 基比分析 salary/first_salary

,LAG(SALARY, 1, 0) OVER(PARTITION BY EMPLOYEENO ORDER BY YEARMONTH) AS PREV_SAL -- 环比分析，与上个月份进行比较

,LAG(SALARY, 12, 0) OVER(PARTITION BY EMPLOYEENO ORDER BY YEARMONTH) AS PREV_12_SAL -- 同比分析，与上个年度相同月份进行比较

,SUM(SALARY) OVER(PARTITION BY EMPLOYEENO, SUBSTR(YEARMONTH, 1, 4) ORDER BY YEARMONTH RANGE UNBOUNDED PRECEDING) LJ --累计值

FROM SALARYBYMONTH

ORDER BY EMPLOYEENO

,YEARMONTH