本文主要是介绍lag() over(partition by ... order by ...)与 lead() over(partition by ... order by ...)的区别，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
举例所需表：
lag() over(partition by … order by …)
该函数的意思是分组排序后，取同组下一行的规定列值。
例子：SELECT employee_id,name,department_id,salary,lead(salary,1) over(PARTITION by department_id order by salary asc) as number1 from employees ;
结果：
lead() over(partition by … order by …)
该函数的意思是分组排序后，取同组上一行的规定列值。
例子：SELECT employee_id,name,department_id,salary,lag(salary,1) over(PARTITION by department_id order by salary asc) as number1 from employees ;
结果：
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