Вывод строк таблицы БД по массиву значений

Предположим ваша таблица: id || text || news_category

Тогда:

select id, `news_category`, text 
from 
(
   select id, `news_category`, text ,
      (@num:=if(@group = `news_category`, @num +1, if(@group := `news_category`, 1, 1))) row_number 
  from table1 t
  CROSS JOIN (select @num:=0, @group:=null) c
  order by `news_category`, id desc, text 
) as x 
where x.row_number <= 2

Ответ по мотивам https://stackoverflow.com/questions/12113699/get-top-n-records-for-each-group-of-grouped-results