WINDOW_FUNCTION_LAST_VALUE

WINDOW FUNCTION LAST_VALUE

description

LAST_VALUE() 返回窗口范围内的最后一个值。与 FIRST_VALUE() 相反。ignore_null 决定是否忽略 null 值，参数 ignore_null 默认值为 false 。

LAST_VALUE(expr[, ignore_null]) OVER(partition_by_clause order_by_clause [window_clause])

example

使用FIRST_VALUE()举例中的数据：

select * , 
last_value(`state`, 1) over(partition by `myday` order by `time_col` DESC rows between 1 preceding and 1 following) as ignore_null,
last_value(`state`, 0) over(partition by `myday` order by `time_col` DESC rows between 1 preceding and 1 following) as not_ignore_null,
last_value(`state`) over(partition by `myday` order by `time_col` DESC rows between 1 preceding and 1 following) as ignore_null_default
from t order by `id`, `myday`, `time_col`;

| id   | myday | time_col    | state | ignore_null | not_ignore_null | ignore_null_default |
|------|-------|-------------|-------|-------------|-----------------|---------------------|
|    1 |    21 | 04-21-11    |  NULL |           2 |            NULL |                NULL |
|    2 |    21 | 04-21-12    |     2 |           2 |            NULL |                NULL |
|    3 |    21 | 04-21-13    |     3 |           2 |               2 |                   2 |
|    4 |    22 | 04-22-10-21 |  NULL |        NULL |            NULL |                NULL |
|    5 |    22 | 04-22-10-22 |  NULL |           5 |            NULL |                NULL |
|    6 |    22 | 04-22-10-23 |     5 |           5 |            NULL |                NULL |
|    7 |    22 | 04-22-10-24 |  NULL |           5 |               5 |                   5 |
|    8 |    22 | 04-22-10-25 |     9 |           9 |            NULL |                NULL |
|    9 |    23 | 04-23-11    |  NULL |          10 |            NULL |                NULL |
|   10 |    23 | 04-23-12    |    10 |          10 |            NULL |                NULL |
|   11 |    23 | 04-23-13    |  NULL |          10 |              10 |                  10 |
|   12 |    24 | 02-24-10-21 |  NULL |        NULL |            NULL |                NULL |

keywords

WINDOW,FUNCTION,LAST_VALUE