Parâmetros dinâmicos para usar com Data Explorer

Funcionaria mover os padrões para a consulta e usá-los enquanto nenhuma data for selecionada? Algo como isto:

-- [params]
-- null date :start_date
-- null date :end_date

SELECT id as topic_id, created_at
FROM topics
WHERE created_at > COALESCE(:start_date, CAST(date_trunc('week', current_date) AS DATE))
AND created_at < COALESCE(:end_date, CAST(date_trunc('week', current_date) AS DATE)+4)