Mysql 我不知道'；我不知道我的错误在哪里；关键字约束附近的语法不正确'；

我相信这只是一个在哪里放置逗号的问题，但我在自学，所以很难弄清楚这一点。

你添加了太多的逗号

CREATE TABLE ClassRegistration(
StudentID int   NOT NULL,
CourseID int    NOT NULL,

CONSTRAINT PK_ClassRegistration PRIMARY KEY (StudentID, CourseID),
CONSTRAINT FK_ClassRegistration_Students,
FOREIGN KEY(StudentID) REFERENCES Students(ID),
ON DELETE CASCADE ON UPDATE CASCADE,

CONSTRAINT FK_ClassRegistration_Classes,
FOREIGN KEY(CourseID) REFERENCES Course(ClassNumber),
ON DELETE CASCADE ON UPDATE CASCADE
)

有关正确语法的信息，请参见此

---

你加了太多的逗号

CREATE TABLE ClassRegistration(
StudentID int   NOT NULL,
CourseID int    NOT NULL,

CONSTRAINT PK_ClassRegistration PRIMARY KEY (StudentID, CourseID),
CONSTRAINT FK_ClassRegistration_Students,
FOREIGN KEY(StudentID) REFERENCES Students(ID),
ON DELETE CASCADE ON UPDATE CASCADE,

CONSTRAINT FK_ClassRegistration_Classes,
FOREIGN KEY(CourseID) REFERENCES Course(ClassNumber),
ON DELETE CASCADE ON UPDATE CASCADE
)

有关正确语法的信息，请参见此

---

约束定义没有“嵌入”逗号：

---

顺便说一句：零件

约束PK\u类注册
是无用的。您不能在MySQL中为主键约束命名（您可以指定它，但它会被忽略并始终命名为
primary
）
约束定义没有“嵌入”逗号：

顺便说一句：零件
约束PK\u类注册
是无用的。您不能在MySQL中为主键约束命名（您可以指定它，但它会被忽略并始终命名为
primary
）
我以前见过相同的逗号问题，您是从教程中学习的吗？我以前见过相同的逗号问题，您是从教程中学习的吗？
CREATE TABLE ClassRegistration(
    StudentID int   NOT NULL,
    CourseID int    NOT NULL,

    PRIMARY KEY (StudentID, CourseID),

    CONSTRAINT FK_ClassRegistration_Classes
    FOREIGN KEY(StudentID) REFERENCES Students(ID) ON DELETE CASCADE ON UPDATE CASCADE,

    CONSTRAINT FK_ClassRegistration_Classes
    FOREIGN KEY(CourseID) REFERENCES Course(ClassNumber) ON DELETE CASCADE ON UPDATE CASCADE
)

CREATE TABLE ClassRegistration
(
   StudentID int   NOT NULL,
   CourseID int    NOT NULL,

   CONSTRAINT PK_ClassRegistration PRIMARY KEY (StudentID, CourseID),

   CONSTRAINT FK_ClassRegistration_Students   --- no comma here
   FOREIGN KEY(StudentID) REFERENCES Students(ID) -- no comma here
   ON DELETE CASCADE ON UPDATE CASCADE,

   CONSTRAINT FK_ClassRegistration_Classes -- no comma here
   FOREIGN KEY(CourseID) REFERENCES Course(ClassNumber) -- no comma here
   ON DELETE CASCADE ON UPDATE CASCADE
);