recursive cte, Sql Server

Language: Layout:

CREATE TABLE NumThings
    ([Id] varchar(1), [Parent] varchar(4), [Description] varchar(9), [NumberOfThings] int, [Number] varchar(4))
;
    
INSERT INTO NumThings
    ([Id], [Parent], [Description], [NumberOfThings], [Number])
VALUES
    ('A', NULL, 'This is A', 1, NULL),
    ('B', NULL, 'This is B', 3, NULL),
    ('C', NULL, 'This is C', 2, NULL)
;

with cte as (
  select Id as BaseId,
         cast(Id as varchar(10)) as Id,
         cast(null as varchar(1)) as Parent,
         Description,
         NumberOfThings,
         NumberOfThings as TotalCount,
         1 as CurrentCount,
         null as Number
    from NumThings
   union all
  select c.BaseId,
         cast(c.BaseId + '-' + cast(c.CurrentCount as varchar(8)) as varchar(10)) as Id,
         c.BaseId as Parent,
         c.Description,
         1 as NumberOfThings,
         c.TotalCount,
         c.CurrentCount + 1 as CurrentCount,
         c.CurrentCount as Number
    from cte c
   where c.CurrentCount <= c.TotalCount
)
select Id,
       Parent,
       Description,
       NumberOfThings,
       Number
  from cte
 order by case when Parent is null then 0 else 1 end,
          Number,
          Id;

View schema
Execution time: 0,02 sec, rows selected: 9, rows affected: 3, absolute service time: 0,17 sec