explain详细说明(二)
NULL,
`i_data` varchar(50) DEFAULT NULL,
PRIMARY KEY (`i_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 ;
CREATE TABLE `orders` (
`o_id` int(11) NOT NULL,
`o_d_id` tinyint(4) NOT NULL,
`o_w_id` smallint(6) NOT NULL,
`o_c_id` int(11) DEFAULT NULL,
`o_entry_d` datetime DEFAULT NULL,
`o_carrier_id` tinyint(4) DEFAULT NULL,
`o_ol_cnt` tinyint(4) DEFAULT NULL,
`o_all_local` tinyint(4) DEFAULT NULL,
PRIMARY KEY (`o_w_id`,`o_d_id`,`o_id`),
KEY `idx_orders` (`o_w_id`,`o_d_id`,`o_c_id`,`o_id`),
CONSTRAINT `fkey_orders_1` FOREIGN KEY (`o_w_id`, `o_d_id`, `o_c_id`) REFERENCES `customer` (`c_w_id`, `c_d_id`, `c_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;