SQL 查看/查询以通过 json 字段连接 2 个表之间的数据

Question

示例 table 结构：

create table issues
(id int, title varchar(50), affectedclients varchar(max))

create table clients
(id int, name varchar(50))

insert into issues (id, title, affectedclients) values (1, 'Error when clicking save', '["1","2"]');
insert into issues (id, title, affectedclients) values (2, '404 error on url', '[3]');

insert into clients (id, name) values (1, 'Tesco');
insert into clients (id, name) values (2, 'Costa');
insert into clients (id, name) values (3, 'Boots');
insert into clients (id, name) values (4, 'Nandos');

我想运行一个查询，这样我就可以得到以下格式的数据：

Id   Title                        AffectedClients
1    Error when clicking save     Tesco, Costa
2    404 error on url             Boots

请问我怎样才能以最高效的方式实现这一点？

如果使用正确规范化的数据库很容易做到这一点，请提供示例。

Answer 1

您需要使用具有显式架构定义的 OPENJSON() 来解析 affectedclients 列中的 JSON 文本。之后，您需要聚合名称（使用 FOR XML PATH 表示 SQL Server 2016+ 或 STRING_AGG() 表示 SQL SQL Server 2017+）。

数据：

create table issues
(id int, title varchar(50), affectedclients varchar(max))
create table clients
(id int, name varchar(50))
insert into issues (id, title, affectedclients) values (1, 'Error when clicking save', '["1","2"]');
insert into issues (id, title, affectedclients) values (2, '404 error on url', '[3]');
insert into clients (id, name) values (1, 'Tesco');
insert into clients (id, name) values (2, 'Costa');
insert into clients (id, name) values (3, 'Boots');
insert into clients (id, name) values (4, 'Nandos');

SQL Server 2016+ 声明：

SELECT 
   i.id, 
   i.title,
   [affectedclients] = STUFF(
      (
      SELECT CONCAT(', ', c.[name])
      FROM OPENJSON(i.affectedclients) WITH (id int '$') j
      LEFT JOIN clients c on c.id = j.id
      FOR XML PATH('')
      ), 1, 2, '')
FROM issues i

SQL Server 2017+ 声明：

SELECT i.id, i.title, STRING_AGG(c.name, ', ') AS affectedclients
FROM issues i
CROSS APPLY OPENJSON(i.affectedclients) WITH (id int '$') j
LEFT JOIN clients c ON c.id = j.id
GROUP BY i.id, i.title
ORDER BY i.id, i.title

结果：

-----------------------------------------------
id  title                       affectedclients
-----------------------------------------------
1   Error when clicking save    Tesco, Costa
2   404 error on url            Boots

SQL 查看/查询以通过 json 字段连接 2 个表之间的数据

SQL view / query to join data between 2 tables via a json field

sql

sql-server

json

sql-server-json