Question

我很难将这两个函数合并到一个查询中，例如：

WITH time_values AS (
    SELECT
        (end_time - start_time) * 1.0 / 3600000000 AS num_hours
    FROM table
    WHERE
        end_time >= 1493596800000000
        AND start_time < 1493683200000000
)

SELECT
    PERCENTILE_DISC(0.25) WITHIN GROUP (ORDER BY num_hours) OVER() AS p25,
    PERCENTILE_DISC(0.50) WITHIN GROUP (ORDER BY num_hours) OVER() AS p50,
    PERCENTILE_DISC(0.80) WITHIN GROUP (ORDER BY num_hours) OVER() AS p80,
    PERCENTILE_DISC(0.99) WITHIN GROUP (ORDER BY num_hours) OVER() AS p99,
    AVG(num_hours)
FROM time_values;

这会返回ERROR: column "time_values.num_hours" must appear in the GROUP BY clause or be used in an aggregate function

Answer 1

AVG()可以是聚合的（需要按某些列分组）和窗口函数（需要frame子句）。出现错误是因为您已经使用窗口函数PERCENTILE并且AVG函数没有frame子句，尽管它并不明显。要在同一查询中使用AVG，您需要模拟看起来像

的子句

AVG(num_hours) OVER (PARTITION BY 1)

你可以在一个Redshift查询中一起使用AVG（）和PERCENTILE_DISC（）函数吗？

1 个答案: