1

示例表结构：

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，以便我可以获取以下格式的数据：

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

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，那么请提供一个示例。

4

1 回答 1

1

您需要使用OPENJSON()显式架构定义来解析列JSON中的文本affectedclients。之后，您需要聚合名称（FOR XML PATH用于 SQL Server 2016+ 或STRING_AGG()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+ 的声明：

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+ 的声明：

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
于 2019-09-27T08:30:44.117 回答