Question

当我尝试在表格中插入日期时遇到此错误。这是我的完整错误：

错误1452（23000）：无法添加或更新子行：外键约束失败（university。course，CONSTRAINT course_ibfk_2 FOREIGN KEY（prerequisite）参考course（course_id））

以下是我的表格：

CREATE TABLE department (
    dept_id INT(1) UNIQUE,
    dept_name VARCHAR(50) NOT NULL,
    budget INT(10) NOT NULL,
    PRIMARY KEY (dept_id))ENGINE=INNODB;



CREATE TABLE term (
    term_id VARCHAR(50) UNIQUE,
    term_desc VARCHAR(50) NOT NULL,
    start_date DATE NOT NULL,
    end_date DATE NOT NULL,
    PRIMARY KEY (term_id))ENGINE=INNODB;



CREATE TABLE major (
    major_id VARCHAR(3) UNIQUE,
    major_desc VARCHAR(50) NOT NULL,
    PRIMARY KEY (major_id))ENGINE=INNODB;



CREATE TABLE location (
    room_id INT(2) UNIQUE,
    building VARCHAR(50) NOT NULL,
    room_no INT(3) NOT NULL,
    capacity INT(2) NOT NULL,
    room_type VARCHAR(1) NOT NULL,
    room_description VARCHAR(50) NOT NULL,
    PRIMARY KEY (room_id))ENGINE=INNODB;

CREATE TABLE course
(
    course_id VARCHAR(6),
    title VARCHAR(30) NOT NULL UNIQUE,
    credits INT(1) NOT NULL,
    dept_id INT(1) NOT NULL AUTO_INCREMENT,
    prerequisite VARCHAR(6),
    PRIMARY KEY (course_id),
    FOREIGN KEY (dept_id) REFERENCES department (dept_id),
    FOREIGN KEY (prerequisite) REFERENCES course (course_id)
)
ENGINE=innodb;

CREATE TABLE faculty
(
    faculty_id INT(5),
    name VARCHAR(30) NOT NULL,
    room_id INT(2),
    dept_id INT(1) NOT NULL,
    salary DECIMAL(8,2),
    PRIMARY KEY (faculty_id),
    FOREIGN KEY (room_id) REFERENCES location (room_id),
    FOREIGN KEY (dept_id) REFERENCES department (dept_id)
)
ENGINE=innodb;


CREATE TABLE student
(
    student_id INT(5),
    last_name VARCHAR(30) NOT NULL,
    first_name VARCHAR(30) NOT NULL,
    street VARCHAR(60),
    city VARCHAR(40),
    state CHAR(2),
    zip VARCHAR(5),
    birth_date DATE,
    major_id VARCHAR(3),
    phone VARCHAR(10),
    student_type ENUM('ugrad','grad'),
    PRIMARY KEY (student_id),
    FOREIGN KEY (major_id) REFERENCES major (major_id)
)
ENGINE=innodb;

CREATE TABLE section
(
    section_id INT(4),
    course_id VARCHAR(6) NOT NULL,
    section_number VARCHAR(2) NOT NULL,
    term_id VARCHAR(4) NOT NULL,
    faculty_id INT(5),
    day VARCHAR(8),
    max_count INT(2),
    start_time TIME,
    end_time TIME,
    room_id INT(2),
    PRIMARY KEY (section_id),
    FOREIGN KEY (course_id) REFERENCES course (course_id),
    FOREIGN KEY (term_id) REFERENCES term (term_id),
    FOREIGN KEY (faculty_id) REFERENCES faculty (faculty_id),
    FOREIGN KEY (room_id) REFERENCES location (room_id)
);

CREATE TABLE registration
(
    student_id INT(5),
    section_id INT(4),
    midterm_grade ENUM('A','B','C','D','F','W'),
    final_grade ENUM('A','B','C','D','F','W'),
    PRIMARY KEY (student_id, section_id),
    FOREIGN KEY (student_id) REFERENCES student (student_id),
    FOREIGN KEY (section_id) REFERENCES section (section_id)
)
ENGINE=innodb;

当我尝试将我的值输入到表格课程，部分和注册中时，我收到错误，而我似乎无法弄清楚如何更正输入值。以下是我尝试插入课程，部分和注册表中的几个输入值：

INSERT INTO course (course_id, title, credits, dept_id, prerequisite)
VALUES ('AC101', 'Accounting', '3', '3', 'EN100')

INSERT INTO section (section_id, course_id, section, term_id, faculty_id, day, max_count, start_time, end_time, room_id)
VALUES ('1101', 'CIS265', '01', 'WN13', '63395', 'MW', '30', '09:00', '10:30', '13')

INSERT INTO registration (student_id, section_id, midterm_grade, final_grade)
VALUES ('24746', '1102', 'B', 'B')

无论何时我尝试在这些表中输入值，我都会得到ERROR 1452（23000）。有人可以帮我理解我错在哪里或者我应该如何输入我的价值观？

Answer 1

 ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails
 (`university`.`course`, CONSTRAINT `course_ibfk_2` 
 FOREIGN KEY (`prerequisite`) REFERENCES `course` (`course_id`))

此错误表示放入prerequisite表的course列的值与course表中的行不匹配。

在添加course_id='EN100'行之前，表格中必须包含prerequisite='EN100'的行。

插入以下行：

INSERT INTO department (dept_id, dept_name, budget) VALUES 
('1', 'Language Arts', NULL);

INSERT INTO course (course_id, title, credits, dept_id, prerequisite) VALUES 
('EN100', 'English Composition', '3', '1', NULL) ;

INSERT INTO department (dept_id, dept_name, budget) VALUES 
('3', 'Business', NULL);

在我们插入此行之前：

INSERT INTO course (course_id, title, credits, dept_id, prerequisite) VALUES 
('AC101', 'Accounting', '3', '3', 'EN100') ;

我在mysql中得到一个ERROR 1452（23000）

1 个答案: