在 Python 3.4 中的 MySQL 中创建表格

Question

我正在运行通过 Apache 使用 Python 3.4 作为 cgi 和 Windows 10 上的 MySQL 数据库服务器连接服务器。当我尝试运行我创建数据库的函数出现错误：

DatabaseError: 1005 (HY000): Can't create table `testdb`.`studentexam` (errno: 150 
"Foreign key constraint is incorrectly formed")

创建数据库的函数

import mysql.connector as conn

#connect to server
db=conn.connect(host="localhost",user="root",password="")
cursor=db.cursor()
#create database
cursor.execute("""CREATE DATABASE IF NOT EXISTS Testdb""")
db.commit()
#use database
cursor.execute("""USE Testdb""")
db.commit()
#create Teacher table
cursor.execute("""CREATE TABLE IF NOT EXISTS Teacher(
    TeacherUsername VARCHAR(255) PRIMARY KEY,
    TeacherPassword TEXT)""")
db.commit()
#create student table
cursor.execute("""CREATE TABLE IF NOT EXISTS Student(
    StudentNo INT PRIMARY KEY,
    StudentSurname TEXT,
    StudentForename TEXT,
    StudentTeacher VARCHAR(255),
    StudentPassword TEXT,
    FOREIGN KEY(StudentTeacher) REFERENCES Teacher(TeacherUsername))""")
db.commit()
#create exam table
cursor.execute("""CREATE TABLE IF NOT EXISTS Exam(
    TestName VARCHAR(255) PRIMARY KEY,
    TestTotalMarks TEXT,
    Teacher VARCHAR(255),
    FOREIGN KEY(Teacher) REFERENCES Teacher(TeacherUsername))""")
db.commit()
#create StudentExam table
cursor.execute("""CREATE TABLE IF NOT EXISTS StudentExam(
    TestName VARCHAR(255),
    StudentID INT,
    StudentTotalMarks INT,
    PRIMARY KEY(TestName,StudentID),
    FOREIGN KEY(TestName) REFERENCES Exam(TestName),
    FOREIGN KEY(StudentID) REFERENCES Student(StudentID))""")
db.commit()
#create ExamSection table
cursor.execute("""CREATE TABLE IF NOT EXISTS ExamSection(
    TestName VARCHAR(255),
    SectionID INT,
    PRIMARY KEY(TestName,SectionID),
    FOREIGN KEY(TestName) REFERENCES Exam(TestName),
    FOREIGN KEY(SectionID) REFERENCES Section(SectionID))""")
db.commit()
#create Section table
cursor.execute("""CREATE TABLE IF NOT EXISTS Section(
    SectionID INT PRIMARY KEY,
    SectionName TEXT,
    SectionTotalMarks INT)""")
db.commit()
#create Question table
cursor.execute("""CREATE TABLE IF NOT EXISTS Question(
    QuestionID INT PRIMARY KEY,
    SectionID VARCHAR(255),
    Image TEXT,
    Question TEXT,
    PossibleAnswer TEXT,
    CorrectAnswer TEXT,
    QuestionType TEXT,
    FOREIGN KEY(SectionID) REFERENCES Section(SectionID))""")
db.commit()
#create QuestionResults Table
cursor.execute("""CREATE TABLE IF NOT EXISTS QuestionResults(
    QuestionID INT,
    StudentID INT,
    SectionID VARCHAR(255),
    StudentAnswer TEXT,
    PRIMARY KEY(QuestionID,StudentID),
    FOREIGN KEY(QuestionID) REFERENCES Question(QuestionID)
    FOREIGN KEY(StudentID) REFERENCES Student(StudentID))""")
db.commit()
#create Revision table
cursor.execute("""CREATE TABLE IF NOT EXISTS Revision(
    RevisionID INT PRIMARY KEY,
    RevisionSheet TEXT,
    TeacherUsername VARCHAR(255),
    FOREIGN KEY(TeacherUsername) REFERENCES Teacher(TeacherUsername))""")
db.commit()
#create StudentRevition table
cursor.execute("""CREATE TABLE IF NOT EXISTS StudentRevision(
    RevisionID INT,
    StudentID INT,
    PRIMARY KEY(RevisionID,StudentID),
    FOREIGN KEY(RevisionID) REFERENCES Revision(RevisionID),
    FOREIGN KEY(StudentID) REFERENCES Student(StudentID))""")
db.commit()
#create StudentResults table
cursor.execute("""CREATE TABLE IF NOT EXISTS StudentResults(
    SectionID VARCHAR(255),
    StudentID INT,
    StudentSectionMarks INT,
    PRIMARY KEY(SectionID,StudentID),
    FOREIGN KEY(SectionID) REFERENCES Section(SectionID),
    FOREIGN KEY(StudentID) REFERENCES Student(StudentID))""")
db.commit()
cursor.close()

编辑：我将 StudentNo 更改为 StudentID，现在出现错误：

DatabaseError: 1005 (HY000): Can't create table `testdb`.`examsection` (errno: 150
"Foreign key constraint is incorrectly formed")

Answer 1

创建 StudentExam 时，您引用的 Student.StudentId 不存在。看起来你更想引用 Student.StudentNo.

编辑：

当您创建 ExamSection 时，您引用了尚不存在的部分 table。将 Section 创建状态上移，以便它在您创建 ExamSection 之前运行并提交。

Answer 2

改变这个：

#create student table
cursor.execute("""CREATE TABLE IF NOT EXISTS Student(
StudentNo INT PRIMARY KEY,
StudentSurname TEXT,
StudentForename TEXT,
StudentTeacher VARCHAR(255),
StudentPassword TEXT,
FOREIGN KEY(StudentTeacher) REFERENCES Teacher(TeacherUsername))""")
db.commit()

对此：

#create student table
cursor.execute("""CREATE TABLE IF NOT EXISTS Student(
StudentID INT PRIMARY KEY,
StudentSurname TEXT,
StudentForename TEXT,
StudentTeacher VARCHAR(255),
StudentPassword TEXT,
FOREIGN KEY(StudentTeacher) REFERENCES Teacher(TeacherUsername))""")
db.commit()

在 Python 3.4 中的 MySQL 中创建表格

Creating tables in MySQL in Python 3.4

python

mysql

cgi