如何在sql server中将数据更新为json数组并选择数据作为json数组

Question

我是 SQL Server 2017 中 JSON 结果的新手。我将 JSON 数组存储在表的一列中。我将 id 的数组保存在该表中，但我想从其他表中更新它的相关文本，所以请帮助我。

create table #subjectList(subjectID int identity(1,1),subjectName varchar(50))
insert into #subjectList(subjectName)
select 'Math' union all
select 'English' union all
select 'Hindi' union all
select 'PC' union all
select 'Physics'

select * from #subjectList

Create table #studentList(studentID int identity(1,1), subjectName varchar(50), choseSubjectList varchar(max))
insert into #studentList(subjectName, choseSubjectList)
Select 'A','["1","2"]'

select * from #studentList

create table #studentWithSubject(studentID int,subjectName varchar(50),choseSubjectIDList varchar(max),choseSubjectNameList varchar(max))

insert into #studentWithSubject(studentID,subjectName,choseSubjectIDList)
Select a.studentID,a.studentID,a.choseSubjectList
from #studentList a

Update #studentWithSubject set choseSubjectNameList=''

select * from #studentWithSubject

这里是#studentWithSubject 输出

studentID   subjectName choseSubjectIDList  choseSubjectNameList
1              1         ["1","2"]          ''

现在我想从#subjectList 更新主题名，输出应该是这样的：

studentID   subjectName choseSubjectIDList  choseSubjectNameList
1              1         ["1","2"]          ["Math","English"]

Answer 1

一种可能的方法是使用 OPENJSON() 和默认架构解析带有 ID 的 JSON 数组，然后生成带有名称的 JSON 数组。带有默认架构的OPENJSON() 返回一个包含key、value 和type 列的表，key 列保存每个项目的索引。请注意，这里的重要部分是以与 IDs JSON 数组中存在的顺序相同的顺序生成名称。您需要使用基于字符串聚合的方法，因为我不认为您可以使用FOR JSON 生成具有标量值的 JSON 数组。

表格：

create table #subjectList(subjectID int identity(1,1),subjectName varchar(50))
insert into #subjectList(subjectName)
select 'Math' union all
select 'English' union all
select 'Hindi' union all
select 'PC' union all
select 'Physics'

Create table #studentList(studentID int identity(1,1), subjectName varchar(50), choseSubjectList varchar(max))
insert into #studentList(subjectName, choseSubjectList)
Select 'A','["1","2"]' union all
Select 'B','["3","2","5"]' union all
Select 'C','["6","2"]'

create table #studentWithSubject(studentID int,subjectName varchar(50),choseSubjectIDList varchar(max),choseSubjectNameList varchar(max))
insert into #studentWithSubject(studentID,subjectName,choseSubjectIDList)
Select a.studentID,a.studentID,a.choseSubjectList
from #studentList a

声明：

UPDATE #studentWithSubject
SET choseSubjectNameList = (
    CONCAT(
       '["',
       STUFF(
          (SELECT CONCAT('","', COALESCE(s.subjectName, ''))
          FROM OPENJSON(#studentWithSubject.choseSubjectIDList) j
          LEFT JOIN #subjectList s ON j.[value] = s.subjectID
          ORDER BY CONVERT(int, j.[key])
          FOR XML PATH('')), 1, 3, ''
       ),
       '"]'
    )   
)

结果：

studentID   subjectName choseSubjectIDList  choseSubjectNameList
1           1           ["1","2"]           ["Math","English"]
2           2           ["3","2","5"]       ["Hindi","English","Physics"]
3           3           ["6","2"]           ["","English"]