BEGIN;

    CREATE TABLE task (

      id       int,

      "type"   text,

      building text,

    );

    CREATE TABLE task_history (

      task_id  int,

      year     int,

      month    int,

      day      int,

      status   text

    );

    SELECT

        task_history.year   -- ou EXTRACT(year from ...) si il y a juste une colonne date

      , task_history.month  -- same

      , task."type"

      , task.building

      , COUNT(CASE task_history.status WHEN 'closed' THEN 1 END) AS nb_closed

      , COUNT(CASE task_history.status WHEN 'reopened' THEN 1 END) AS nb_reopened

    FROM task

    JOIN task_history

      ON task.id = task_history.task_id

    GROUP BY

        task_history.year   -- ou EXTRACT(year from ...) si il y a juste une colonne date

      , task_history.month  -- same

      , task."type"

      , task.building

    ORDER BY

        task_history.year   -- ou EXTRACT(year from ...) si il y a juste une colonne date

      , task_history.month  -- same

      , task."type"

      , task.building