在两个表之间的 postgres 中加入、聚合和转换

Question

这是我的两个 table：[两个 table 中的所有列都是 "text" 类型，Table 名称和列名称在粗体。

姓名

--------------------------------
Name     |    DoB   |     Team |
--------------------------------
Harry    |  3/12/85 |  England  
Kevin    |  8/07/86 |  England  
James    |  5/05/89 |  England

分数

------------------------
ScoreName  |   Score   
------------------------
James-1    |   120      
Harry-1    |   30      
Harry-2    |   40      
James-2    |   56

我需要的最终结果是 table 具有以下内容

NameScores

---------------------------------------------
Name     |    DoB   |     Team |   ScoreData
---------------------------------------------
Harry    |  3/12/85 |  England  | "{"ScoreName":"Harry-1", "Score":"30"}, {"ScoreName":"Harry-2", "Score":"40"}" 
Kevin    |  8/07/86 |  England  | null
James    |  5/05/89 |  England  | "{"ScoreName":"James-1", "Score":"120"}, {"ScoreName":"James-2", "Score":"56"}"

我需要使用一个 SQL 命令来创建实体化视图。

我已经意识到它将涉及 string_agg、JOIN 和 JSON 的组合，但未能完全破解它。请帮助:)

Answer 1

我认为 join 并不棘手。复杂的是构建 JSON 对象：

select n.name, n.dob, n.team,
       json_agg(json_build_object('ScoreName', s.name,
                                  'Score', s.score)) as ScoreData
from names n left join
     scores s
     ons.name like concat(s.name, '-', '%')
group by n.name, n.dob, n.team;

注意：json_build_object() 是在 Postgres 9.4 中引入的。

编辑：

我想你可以添加一个 case 语句来获得简单的 NULL:

       (case when s.name is null then NULL
             else json_agg(json_build_object('ScoreName', s.name,
                                             'Score', s.score))
        end) as ScoreData

Answer 2

使用 json_agg() 和 row_to_json() 将分数数据汇总为 json 值：

select n.*, json_agg(row_to_json(s)) "ScoreData"
from "Names" n
left join "Scores" s
on n."Name" = regexp_replace(s."ScoreName", '(.*)-.*', '')
group by 1, 2, 3;

 Name  |   DoB   |  Team   |                                 ScoreData                                 
-------+---------+---------+---------------------------------------------------------------------------
 Harry | 3/12/85 | England | [{"ScoreName":"Harry-1","Score":30}, {"ScoreName":"Harry-2","Score":40}]
 James | 5/05/89 | England | [{"ScoreName":"James-1","Score":120}, {"ScoreName":"James-2","Score":56}]
 Kevin | 8/07/86 | England | [null]
(3 rows)

在两个表之间的 postgres 中加入、聚合和转换

JOIN, aggregate and convert in postgres between two tables

sql

postgresql

join

materialized-views