SQL Server 2016 中使用 JSON 的两列字符串聚合

Question

我的结果包含如下数据：

CustomerId | Rating (Star) | RatingCount
  1        |   1           |   20
  1        |   2           |   15
  1        |   3           |   4
  1        |   4           |   30
  1        |   5           |   36
  2        |   1           |   5
  2        |   2           |   4
  2        |   5           |   10

但我想将结果转换为：

CustomerId  | CustomerRatings
   1        | { "1": 20, "2": 15, "3": 4 , "4": 30, "5": 36 }
   2        | { "1": 5, "2": 4, "5": 10 }

我使用 FOR JSON 路径函数将数据转换为

@JSONString = {"_":"1","__":20},{"_":"2","__":15},{"_":"3","__":4},{"_":"4","__":30},{"_":"5","__":36}

然后使用replace方法得到实际结果。

SELECT REPLACE(REPLACE(REPLACE(@JSONString,'"_":',''),',"__":',':'),'},{',',')

{"1":20,"2":15,"3":4,"4":30,"5":36}

有没有更好的方法来实现？我最近几天开始使用 SQL server 2016。

Answer 1

假设评分总是在 1 到 5 之间：

SELECT CustomerId, (
    SELECT MIN(CASE WHEN Rating = 1 THEN RatingCount END) AS [1]
         , MIN(CASE WHEN Rating = 2 THEN RatingCount END) AS [2]
         , MIN(CASE WHEN Rating = 3 THEN RatingCount END) AS [3]
         , MIN(CASE WHEN Rating = 4 THEN RatingCount END) AS [4]
         , MIN(CASE WHEN Rating = 5 THEN RatingCount END) AS [5]
    FROM t AS x
    WHERE x.CustomerId = t.CustomerId
    FOR JSON AUTO, WITHOUT_ARRAY_WRAPPER
)
FROM t
GROUP BY CustomerId

使用 INCLUDE_NULL_VALUES 选项来包含空值，或 COALESCE(..., 0) 将空值转换为零。

Demo on db<>fiddle

SQL Server 2016 中使用 JSON 的两列字符串聚合

String aggregation with two columns using JSON in SQL Server 2016

tsql

sql-server

json

string-aggregation

sql-server-2016