Question

我想知道是否可以在PostgreSQL中将2个查询结果比较为1个。例如：我有整个3月的数据，然后又有4月的整个月的数据。

此查询是我用来获取3月份数据的查询：

    SELECT availability_date, ROUND(AVG(availability_percentage),2)
FROM dashboard.availability
WHERE availability_date BETWEEN '2020-03-01' AND '2020-04-01'
GROUP BY availability_date
ORDER BY availability_date ASC

然后这就是我用来获取4月份数据的那个：

SELECT availability_date, ROUND(AVG(availability_percentage),2)
FROM dashboard.availability
WHERE availability_date BETWEEN '2020-04-01' AND '2020-05-01'
GROUP BY availability_date
ORDER BY availability_date ASC

是否可以将它们合并为一个数据，以便我可以在两个月显示结果？例如：

Month     percentage
March      100%
February   85%

Answer 1

是的，请使用条件聚合：

SELECT
    ROUND(AVG(availability_percentage)
       FILTER (WHERE availability_date BETWEEN '2020-03-01' AND '2020-04-01') , 2) AS avg_march,
    ROUND(AVG(availability_percentage)
       FILTER (WHERE availability_date BETWEEN '2020-04-01' AND '2020-05-01'), 2) AS avg_april
FROM dashboard.availability
WHERE availability_date BETWEEN '2020-03-01' AND '2020-05-01';

请注意，您应该不按日期进行汇总，因为要获取的平均值跨越多个日期。

在查询PostgreSQL中比较2个查询结果

1 个答案: