postgres：関数クエリの動的条件付き

Question

私は関数に渡された条件付きパラメータを動的に追加する必要があるPostgres関数を持っています。ここでは機能があります：for_staff_idが関数に渡され

CREATE OR REPLACE FUNCTION public.get_appointments(
    for_business_id INTEGER, 
    range_start DATE, 
    range_end DATE, 
    for_staff_id INTEGER 
    ) 
     RETURNS SETOF appointment 
     LANGUAGE plpgsql STABLE 
     AS $function$ 
    DECLARE 
     appointment appointment; 
     recurrence TIMESTAMP; 
     appointment_length INTERVAL; 
     parent_id UUID; 
    BEGIN 
     FOR appointment IN 
      -- NEED TO CONDITIONALLY ADD "WHERE staff_id = for_staff_id" 
      -- if for_staff_id is NOT NULL 
      SELECT * 
       FROM appointment 
      WHERE business_id = for_business_id 
       AND (
         recurrence_pattern IS NOT NULL 
        OR (
          recurrence_pattern IS NULL 
         AND starts_at BETWEEN range_start AND range_end 
        ) 
       ) 
     LOOP 
      IF appointment.recurrence_pattern IS NULL THEN 
       RETURN NEXT appointment; 
       CONTINUE; 
      END IF; 

      appointment_length := appointment.ends_at - appointment.starts_at; 
      parent_id := appointment.id; 

      FOR recurrence IN 
       SELECT * 
        FROM generate_recurrences(
          appointment.recurrence_pattern, 
          appointment.starts_at, 
          range_start, 
          range_end 
       ) 
      LOOP 
       EXIT WHEN recurrence::date > range_end; 
       CONTINUE WHEN (recurrence::date < range_start AND recurrence::date > range_end) OR recurrence = ANY(appointment.recurrence_exceptions); 
       appointment.id := uuid_generate_v5(uuid_nil(), parent_id::varchar || recurrence::varchar); 
       appointment.parent_id := parent_id; 
       appointment.starts_at := recurrence; 
       appointment.ends_at := recurrence + appointment_length; 
       appointment.recurrence_pattern := appointment.recurrence_pattern; 
       appointment.recurrence_exceptions := NULL; 
       appointment.is_recurrence := true; 
       RETURN NEXT appointment; 
      END LOOP; 
     END LOOP; 
     RETURN; 
    END; 
    $function$; 

場合、私はFOR...INループに位置し、クエリに条件（WHERE staff_id = for_staff_id）として追加する必要があります。私はFOR...INの中でIF/ELSEを実行しようとしましたが、構文エラーが発生しています。

これを行うより良い方法はありますか？

ありがとうございます！

私はPostgres 9.5を実行しています。

Answer 1

だけSELECT文のWHERE句に次

... AND (for_staff_id IS NULL OR staff_id = for_staff_id) 

またはこの

... AND coalesce(staff_id = for_staff_id, true) 

を追加します。