常见分析窗口函数： ```sql cume_dist() -- 小于等于当前值的行数/分组内总行数 lead(col, n) -- 某一列进行往前第 n 行值(n 可选，默认为 1) lag(col, n) -- 某一列进行往后第 n 行值(n 可选，默认为 1) first_value() -- 对该列到目前为止的首个值 last_value() -- 到目前行为止的最后一个值 ``` ```sql select * from logs; +----------+-----------+--+ | logs.id | logs.num | +----------+-----------+--+ | 1 | 1 | | 2 | 1 | | 3 | 1 | | 4 | 2 | | 5 | 1 | | 6 | 2 | | 7 | 2 | +----------+-----------+--+ select num, lead(num, 1) over() as num1, lead(num, 2) over() as num2 from logs; +------+-------+-------+--+ | num | num1 | num2 | +------+-------+-------+--+ | 2 | 2 | 1 | | 2 | 1 | 2 | | 1 | 2 | 1 | | 2 | 1 | 1 | | 1 | 1 | 1 | | 1 | 1 | NULL | | 1 | NULL | NULL | +------+-------+-------+--+ ```