Пример выборки полей из временной таблицы со всеми параметрами.
Идентично можно выбирать и для обычных таблиц.

Select c.column_id
    ,c.name   [column_name]
    ,y.name   [data_type]
    ,c.max_length
    ,c.precision
    ,c.scale
    ,c.is_identity
    ,c.is_nullable
    ,c.collation_name
  ,', ['+c.name +'] ['+y.name+']'
  +IIF (y.name in ('varchar','char'),'('+cast(IIF(c.max_length=0,'max',c.max_length) as varchar(5))+')','')
  +IIF (y.name in ('nvarchar'),'('+cast(IIF(c.max_length=0,'max',c.max_length/2) as varchar(5))+')','')
  +IIF (y.name in ('decimal','numeric'),'('+cast(c.precision as varchar(3))+', '+cast(c.scale as varchar(3))+')','')
  +IIF (not y.collation_name is null,' COLLATE '+y.collation_name,'')
  +IIF (y.is_nullable = 1,' NULL','')
  as [ready_column]
 From tempdb.sys.columns c 
 Inner join sys.types y ON y.system_type_id = c.system_type_id
 WHERE c.object_id = Object_id('tempdb..#tmp')
   and y.name!='sysname'
   order by c.column_id

#tmp - ваша временная таблица