select count(distinct t.patient_id) from topic t inner join category c on t.category_id = c.id where 1=1 and date_trunc('month', t.insert_timestamp) = date_trunc('month', '2011-08-01'::timestamp) and t.posted_from_system in ('i', 'k', 'v') and t.patient_id in (select id from patient where date_trunc('month', insert_timestamp) = date_trunc('month', '2011-08-01'::timestamp) and registered_from_system in ('i','v','k')) ;
select count(distinct t.patient_id) from topic t inner join category c on t.category_id = c.id where 1=1 and date_trunc('month', t.insert_timestamp) = date_trunc('month', '2011-08-01'::timestamp) and t.posted_from_system in ('i', 'k', 'v') and t.patient_id in (select id from patient where date_trunc('month', insert_timestamp) = date_trunc('month', '2011-08-01'::timestamp) and registered_from_system in ('i','v','k')) ;
月間ユニーク質問者数=13381 月間有効会員数=127893
PCの HTML メール画像は img タグ経由でダウンロードする img タグのリクエストで開封率をカウント 一方、モバイル HTML メールは添付ファイルで画像を表示させる