MySQL: Fechas

SELECT * FROM mitabla
WHERE fecha_creacion BETWEEN '2013-11-26 18:00:00' AND '2014-12-31 18:00:00' limit 0,200 


// saca los últimos 30 días
select * from mitabla where fh_alta BETWEEN (date_sub(NOW(), INTERVAL 30 DAY)) AND NOW()


Funciones:
date_sub(..., ...);
date_add(..., ...);

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select * from mitabla where fh_alta < NOW()