Question

SELECT
    externalsource.id,
    externalsource.url,
    externalsource.last_fetch,
    SUM(scripttracking.records) AS jobs_per_week
FROM
    scripttracking
RIGHT JOIN
    externalsource
ON
    externalsource.script_name = scripttracking.script_name
AND
    scripttracking.created_on > %s
GROUP BY
    externalsource.id

任何想法如何修改此查询以便它将使用不同的“AND”条件聚合scripttracking.records？

基本上，我需要得到的是：

SUM(scripttracking.records) for scripttracking.created_on > now() - 1 week

SUM(scripttracking.records) for scripttracking.created_on > now() - 1 month

SUM(scripttracking.records) for scripttracking.created_on > now() - 1 year

我需要在1个结果查询集中包含所有这些字段。

类似的东西：

ID, URL, LAST_FETCH, JOBS_PER_WEEK, JOBS_PER_MONTH, JOBS_PER_YEAR
1, http://google.ru, 25/01/2016, 7, 23, 8889

Answer 1

传统上我们会使用CASE声明，但Postgres为我们提供了更舒适的解决方案，因此最好使用FILTER

SELECT
    externalsource.id
    ,externalsource.url
    ,externalsource.last_fetch
    ,SUM(scripttracking.records) AS jobs_per_week
    ,SUM(scripttracking.records) FILTER (WHERE scripttracking.created_on > now() - 1 week)
    ,SUM(scripttracking.records) FILTER (WHERE scripttracking.created_on > now() - 1 month)
    ,SUM(scripttracking.records) FILTER (WHERE scripttracking.created_on > now() - 1 year)
FROM
    scripttracking
RIGHT JOIN
    externalsource
ON
    externalsource.script_name = scripttracking.script_name
AND
    scripttracking.created_on > %s
GROUP BY
    externalsource.id

Answer 2

使用case语句来计算要求的值，否则使用0。

请注意，这是包含逻辑，因此月份总和包含一周的总和，而年份的总和包含一些星期和月份。

SELECT
    externalsource.id,
    externalsource.url,
    externalsource.last_fetch,
    SUM(case when scripttracking.created_on > now() - 1 week then scripttracking.records else 0 end) AS jobs_per_week,
    SUM(case when scripttracking.created_on > now() - 1 month then scripttracking.records else 0 end) AS jobs_per_Month,
    SUM(case wehn scripttracking.created_on > now() - 1 year then scripttracking.records else 0 end) AS jobs_per_Year
FROM
    scripttracking
RIGHT JOIN
    externalsource
ON
    externalsource.script_name = scripttracking.script_name
AND
    scripttracking.created_on > %s
GROUP BY
    externalsource.id

Answer 3

您可以简单地使用case语句来获取不同列的聚合。简而言之，这可以写成：

SELECT
    externalsource.id,
    externalsource.url,
    externalsource.last_fetch,
    SUM(scripttracking.records) for scripttracking.created_on > now() [JOBS_PER_WEEK], 
SUM(scripttracking.records) for scripttracking.created_on > now() [JOBS_PER_MONTH],
SUM(scripttracking.records) for scripttracking.created_on > now() [JOBS_PER_YEAR]
from 
..... your rest of your query goes here.

如何在RIGHT JOIN中聚合具有不同AND子句的字段？

3 个答案: