通常删除表中的内容，可以使用如下命令
SQL> delete from tbl_name; 删除表中所有数据，但效率比较慢
SQL> TRUNCATE tbl_name; 删除表中所有数据，重建表结构，比较快
SQL> delete * from tbl_name where 条件 oder by [asc|desc] limit 数量
满足条件的记录排序后，删除指定数量的条数
例如，删除nagios_servicechecks表中的日期为2010-01-07的记录，方法如下：
mysql> desc nagios_servicechecks;
+-----------------------+---------------+------+-----+---------------------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------------------+---------------+------+-----+---------------------+----------------+
| servicecheck_id | int(11) | NO | PRI | NULL | auto_increment |
| instance_id | smallint(6) | NO | MUL | 0 | |
| service_object_id | int(11) | NO | MUL | 0 | |
| check_type | smallint(6) | NO | | 0 | |
| current_check_attempt | smallint(6) | NO | | 0 | |
| max_check_attempts | smallint(6) | NO | | 0 | |
| state | smallint(6) | NO | | 0 | |
| state_type | smallint(6) | NO | | 0 | |
| start_time | datetime | NO | MUL | 0000-00-00 00:00:00 | |
| start_time_usec | int(11) | NO | | 0 | |
| end_time | datetime | NO | | 0000-00-00 00:00:00 | |
| end_time_usec | int(11) | NO | | 0 | |
| command_object_id | int(11) | NO | | 0 | |
| command_args | varchar(255) | NO | | | |
| command_line | varchar(255) | NO | | | |
| timeout | smallint(6) | NO | | 0 | |
| early_timeout | smallint(6) | NO | | 0 | |
| execution_time | double | NO | | 0 | |
| latency | double | NO | | 0 | |
| return_code | smallint(6) | NO | | 0 | |
| output | varchar(255) | NO | | | |
| long_output | varchar(8192) | NO | | | |
| perfdata | varchar(255) | NO | | | |
+-----------------------+---------------+------+-----+---------------------+----------------+
23 rows in set (0.00 sec)
mysql>delete from nagios_servicechecks where left(end_time,10)= '2010-01-07'
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