id_client	nb_event	update_date	visit_date	id_client	nb_event
1	0	NULL	2010-09-08 00:00:00	1	3
2	0	NULL	2010-09-08 00:00:00	2	2
id_client	nb_event	update_date	visit_date	id_client	nb_event
1	3	2010-12-11 00:00:00	2010-09-08 00:00:00	1	3
2	2	2010-12-11 00:00:00	2010-09-08 00:00:00	2	2