SQL Server 2016 for JSON输出整数数组

Question

我想使用SQL Server 2016的For JSON功能获取带有整数数组的JSON .我对整数数组感到困惑.

数据库表结构:

declare @Employees table (ID int, Name nvarchar(50))
insert into @Employees values
(1, 'Bob'),
(2, 'Randy')

declare @Permissions table (ID int, PermissionName nvarchar(50))
insert into @Permissions values
(1, 'Post'),
(2, 'Comment'),
(3, 'Edit'),
(4, 'Delete')

declare @EmployeePermissions table (EmployeeID int, PermissionID int)
insert into @EmployeePermissions values
(1, 1),
(1, 2),
(2, 1),
(2, 2),
(2, 3)

期望的结果:

{"EmployeePermissions": [
  {"Employee":"Bob", "Permissions":[1,2]},
  {"Employee":"Randy", "Permissions":[1,2,3]}
}

这是我得到的最接近的,但不是我想要的.

select
    e.Name as Employee,
    (select 
         convert(nvarchar(10),ep.PermissionID) as PermID 
     from @EmployeePermissions ep 
     where ep.EmployeeID=e.ID 
     for json path) as 'Permissions'
from
    @Employees e
for json path, root('EmployeePermissions')

收益:

{"EmployeePermissions": [
  {"Employee":"Bob", "Permissions":[{"permID":1},{"permID":2}]},
  {"Employee":"Randy", "Permissions":[{"permID":1},{"permID":2},{"permID":3}]}
}

Answer 1

在AdventureWorks 2016 CTP3 JSON示例中,您可以找到一个可以清除键:值对的数组并创建数组od值的函数:

DROP FUNCTION IF EXISTS dbo.ufnToRawJsonArray
GO
CREATE FUNCTION
[dbo].[ufnToRawJsonArray](@json nvarchar(max), @key nvarchar(400)) returns nvarchar(max)
AS BEGIN
       declare @new nvarchar(max) = replace(@json, CONCAT('},{"', @key,'":'),',')
       return '[' + substring(@new, 1 + (LEN(@key)+5), LEN(@new) -2 - (LEN(@key)+5)) + ']'
END

只需将SELECT FOR JSON表达式的结果作为@json参数和要作为第二个参数删除的键的名称.可能是这样的:

select
e.Name as Employee,
JSON_QUERY(dbo.ufnToRawJsonArray(
    (select 
     convert(nvarchar(10),ep.PermissionID) as PermID 
     from @EmployeePermissions ep 
     where ep.EmployeeID=e.ID 
     for json path)
  , 'PermID'))
   as 'Permissions'
from
@Employees e
for json path, root('EmployeePermissions')

Answer 2

这应该适用于SQL Server 2017 (14.x) 及更高版本

SELECT '[' + STRING_AGG(ep.PermissionID, ',') + ']'
FROM @EmployeePermissions ep

仅当结果字符串超过 8000 字节时，才必须将值转换为 NVarchar(max)

SELECT '[' + STRING_AGG(cast(ep.PermissionID AS NVARCHAR(MAX)), ',') + ']'
FROM @EmployeePermissions ep

完整查询

SELECT e.Name as Employee,
    (SELECT 
         '[' + STRING_AGG(cast(ep.PermissionID AS NVARCHAR(MAX)), ',') + ']' 
     FROM @EmployeePermissions ep 
     WHERE ep.EmployeeID=e.ID) as Permissions 
FROM
    @Employees e
FOR JSON PATH, root('EmployeePermissions')