group_concat函数删除重复项

Question

在BigQuery中创建了以下查询：

There was an error while trying to load the gem 'bootstrap'.
Gem Load Error is: Could not find a JavaScript runtime. See https://github.com/rails/execjs for a list of available runtimes."

作为临时措施，我正在使用having子句对其进行测试（这将在生产中删除）查询输出以下内容：

这一切都很棒并按预期工作，以适当的顺序（平板电脑，平板电脑，平板电脑，手机，桌面）输出设备 - 但是，我想从中删除重复项，因此结果将是“平板电脑，移动设备，桌面“

我尝试使用Unique（）函数，这会删除重复项，但订单不会保留，因此输出变为“桌面，移动设备，平板电脑”

任何帮助将不胜感激！

更新

我将查询更新为标准SQL，现在我使用string_agg（）函数面临另一个问题：

require "execjs"
ExecJS.eval "'red yellow blue'.split(' ')'"

返回的错误是“具有DISTINCT和ORDER BY参数的聚合函数只能ORDER BY作为函数参数的列”

显然，如果我们从string_agg中删除distinct或order by子句，这是有效的，但我们需要这两个操作。

Answer 1

对于更新的问题，以下查询会产生相同的错误：

SELECT age_midpoint, STRING_AGG(DISTINCT country ORDER BY c DESC)
FROM (
  SELECT country, age_midpoint, COUNT(*) c
  FROM `fh-bigquery.stackoverflow.survey_results_2016`
  WHERE age_midpoint IS NOT null
  AND country LIKE '%u%'
  GROUP BY 1, 2
)
GROUP BY 1
ORDER BY 1

这种限制是有道理的，因为一旦你运行DISTINCT，就会失去对你想要提供订单的变量的可见性。

请改为尝试：

#standardSQL
SELECT age_midpoint, ARRAY_TO_STRING(ARRAY(
  SELECT country FROM (SELECT country, c FROM UNNEST(arr) GROUP BY country, c) ORDER BY c DESC
), ',')
FROM (
  SELECT age_midpoint, ARRAY_AGG(STRUCT(country, c)) arr
  FROM (
    SELECT country, age_midpoint, COUNT(*) c
    FROM `fh-bigquery.stackoverflow.survey_results_2016`
    WHERE age_midpoint IS NOT null
    AND country LIKE '%u%'
    GROUP BY 1, 2
  )
  GROUP BY 1
)
ORDER BY 1
LIMIT 1000

（见https://cloud.google.com/bigquery/docs/reference/standard-sql/arrays#creating-arrays-from-subqueries）

Answer 2

感谢Felipe，这是完成的查询！

SELECT
date, value, SUM(visits) visits, STRING_AGG(DISTINCT seqdevice) seqdevice, COUNT(DISTINCT seqdevice) countseqdevice
FROM (
SELECT date, value, visits, ARRAY_TO_STRING(ARRAY(
  SELECT deviceCategory FROM (SELECT deviceCategory, c FROM UNNEST(arr) GROUP BY deviceCategory, c) ORDER BY c DESC
), ',') seqdevice
FROM (
SELECT date, visitStartTime, value, visits, ARRAY_AGG(STRUCT(deviceCategory, c)) arr
FROM (
    SELECT date, visitStartTime, cd.value value, totals.visits visits, device.deviceCategory deviceCategory, COUNT(*) c
    FROM `xxxxxxxxxx`, UNNEST(customDimensions) AS cd
    WHERE cd.index=1 AND STARTS_WITH(cd.value,"hip|")
    GROUP BY 1, 2, 3, 4, 5
    )
GROUP BY 1, 2, 3, 4
)
ORDER BY 2)
 GROUP BY 1, 2
HAVING
  value="hip|7e4fbce9-bbfb-4677-aab0-dcd02851fdb4"

ORDER BY countseqdevice desc