DELETE FROM falta_histo_mat WHERE falta_histo_mat.num_hor=0 OR 
				((id_alu,cod_cur,cod_mat,tip_fal)=(1088972028,2122,6,'t')
				and (fec_fal>= (SELECT fec_ini FROM periodo WHERE id_peri=2) and 
				fec_fal<=(SELECT fec_cor_tot FROM periodo WHERE id_peri=2)))