SQL Server SELECT to JSON function

Starting from SQL Server 2016 you can use for json:

declare @t table(id int, name nvarchar(max), active bit)
insert @t values (1, 'Bob Jones', 1), (2, 'John Smith', 0)

select id, name, active
from @t
for json auto

With older versions of SQL Server you can use for xml path, e.g.:

select '[' + STUFF((
        select 
            ',{"id":' + cast(id as varchar(max))
            + ',"name":"' + name + '"'
            + ',"active":' + cast(active as varchar(max))
            +'}'

        from @t t1
        for xml path(''), type
    ).value('.', 'varchar(max)'), 1, 1, '') + ']'

Output:

[{"id":1,"name":"Bob Jones","active":1},{"id":2,"name":"John Smith","active":0}]

Just for improving answer with latest technology change. with sql server 2016

select id, name ,active 
    from  tableName 
      FOR JSON AUTO