WINDOW FUNCTION AVG

description

计算窗口内数据的平均值

1. AVG([DISTINCT | ALL] *expression*) [OVER (*analytic_clause*)]

example

计算当前行和它前后各一行数据的x平均值

1. select x, property,
2. avg(x) over
3. (
4. partition by property
5. order by x
6. rows between 1 preceding and 1 following
7. ) as 'moving average'
8. from int_t where property in ('odd','even');

10. | x  | property | moving average |
11. |----|----------|----------------|
12. | 2  | even     | 3              |
13. | 4  | even     | 4              |
14. | 6  | even     | 6              |
15. | 8  | even     | 8              |
16. | 10 | even     | 9              |
17. | 1  | odd      | 2              |
18. | 3  | odd      | 3              |
19. | 5  | odd      | 5              |
20. | 7  | odd      | 7              |
21. | 9  | odd      | 8              |

keywords

1. WINDOW,FUNCTION,AVG