我有这 3 张桌子
CREATE TABLE IF NOT EXISTS `enrollment` (
`STUDENT_NUM` varchar(10) NOT NULL,
`SUBJECT_NUM` varchar(10) NOT NULL,
`UNITS` int(10) NOT NULL,
`DAYS` varchar(50) NOT NULL,
`TIME_START` time NOT NULL,
`TIME_END` time NOT NULL,
`ROOM_ID` int(11) DEFAULT NULL,
`PRELIM` float(10,2) DEFAULT NULL,
`MIDTERM` float(10,2) DEFAULT NULL,
`FINALS` float(10,2) DEFAULT NULL,
`FINAL_GRADE` float(10,2) DEFAULT NULL,
`SEMESTER` varchar(50) NOT NULL,
`SCHOOL_YEAR` varchar(50) NOT NULL,
`DATE_ADDED` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`STUDENT_NUM`,`SUBJECT_NUM`),
KEY `SUBJECT_NUM` (`SUBJECT_NUM`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE IF NOT EXISTS `subjects` (
`SUBJECT_NUM` varchar(10) NOT NULL,
`EMPLOYEE_NUM` varchar(10) NOT NULL,
`SUBJECT_TITLE` varchar(100) DEFAULT NULL,
`DEPARTMENT` varchar(100) DEFAULT NULL,
`UNITS` int(10) NOT NULL,
`DAYS` varchar(50) NOT NULL,
`TIME_START` time NOT NULL,
`TIME_END` time NOT NULL,
`room_id` int(11) DEFAULT NULL,
`SEMESTER` varchar(50) NOT NULL,
`SCHOOL_YEAR` varchar(50) NOT NULL,
`COUNT` int(10) DEFAULT NULL,
`STATUS` varchar(50) DEFAULT NULL,
`FLAG` varchar(50) NOT NULL,
`DATE_ADDED` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`SUBJECT_NUM`),
UNIQUE KEY `SUBJECT_NUM` (`SUBJECT_NUM`),
KEY `EMPLOYEE_NUM` (`EMPLOYEE_NUM`),
KEY `EMPLOYEE_NUM_2` (`EMPLOYEE_NUM`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE IF NOT EXISTS `room` (
`ID` int(11) NOT NULL AUTO_INCREMENT,
`room` varchar(255) NOT NULL,
PRIMARY KEY (`ID`),
UNIQUE KEY `room` (`room`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=13 ;
我想要做的是从注册和科目外键中创建字段 ROOM_ID,并且引用是房间的 ID .. ROOM_ID 不能是唯一的......
我收到这个错误
#1452 - Cannot add or update a child row: a foreign key constraint fails (`enrollmentdb`.`#sql-277_164`, CONSTRAINT `#sql-277_164_ibfk_3` FOREIGN KEY (`ROOM_ID`) REFERENCES `room` (`ID`))
当我使用这个 SQL 命令时:
ALTER TABLE enrollment
ADD FOREIGN KEY (room_id)
REFERENCES room(ID)