如何在行中插入外键？

Question

--
-- Table structure for table `sector`
--

CREATE TABLE IF NOT EXISTS `sector` (
  `sector_id` int(11) NOT NULL AUTO_INCREMENT,
  `sector_name` varchar(100) NOT NULL,
  `sector_url` varchar(500) NOT NULL,
  PRIMARY KEY (`sector_id`),
  UNIQUE KEY `sector_id` (`sector_id`,`sector_name`,`sector_url`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;


CREATE TABLE IF NOT EXISTS `constituent` (
  `constituent_id` int(11) NOT NULL AUTO_INCREMENT,
  `constituent_name` varchar(100) DEFAULT '',
  `constituent_ticker` varchar(10) NOT NULL,
  `constituent_isin_number` varchar(50) DEFAULT '',
  `constituent_currency` varchar(10) DEFAULT '',
  `sector_id` int(11) NOT NULL,
  PRIMARY KEY (`constituent_id`),
  KEY `sector_id` (`sector_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;


--
-- Constraints for table `constituent`
--
ALTER TABLE `constituent`
  ADD CONSTRAINT `constituent_ibfk_1` FOREIGN KEY (`sector_id`) REFERENCES `sector` (`sector_id`);

INSERT into constituent (constituent_name, constituent_ticker, constituent_isin_number, constituent_currency, sectorFK) 
values ("the name", "the ticker", "the number", "the currency", "the foreign key???")   

Answer 1

为了能够在插入到表b后获得主键值，为了将其插入到表a，可以使用last_insert_id()函数，在不带参数的情况下使用该函数，该函数返回为auto_increment列设置的最后一个自动生成的值：

例如：

insert into B(col)
  values(1);

insert into A(t1_id, col)
  values(last_insert_id(), 2);

insert into A(t1_id, col)
  values(last_insert_id(), 3);

SQLFIddle演示