SELECT
   toStartOfMonth(DATE) AS MONTH
   ,uniq(
     toUInt32OrZero(
          multiIf( EXTRACT(request_uri, '/category/[a-z\-]*([0-9]{2,7}).*')<>''
            , EXTRACT(request_uri, '/category/[a-z\-]*([0-9]{2,7}).*')
            , extractURLParameter(request_uri, 'category_id')<>''
            , extractURLParameter(request_uri, 'category_id')
            , extractURLParameter(request_uri, 'categories_id')<>''
            , extractURLParameter(request_uri, 'categories_id')
            , visitParamExtractString(post_params, 'categories_id') <> ''
            , visitParamExtractString(post_params, 'categories_id')
            , ''

              )
          ) AS categories_id
      ) AS unq_categories_id
  , uniq(customers_id)  AS unq_customers_id
  , uniq(concat(toString(categories_id),'_', toString(customers_id))) AS cnt_view_categories
, multiIf(
    MATCH(user_agent, 'MamsyApp'), 'MamsyApp'
  , MATCH(user_agent, 'iPhone|iPad|iPod|Android|Windows Phone'), 'Mobile'
  , 'Desktop'
  )            AS platform
FROM site_request AS sr

WHERE customers_id != 0
  AND DATE >= '2019-01-01'
  AND categories_id IS NOT NULL
  AND categories_id != 0
  AND date_added >= dictGetDateTime('categories','date_start',toUInt64( categories_id ))
  AND date_added <= dictGetDateTime('categories','date_end',toUInt64( categories_id ))
GROUP BY  MONTH, platform

-- having unq_customers_id > 20

;