關鍵字'CONSTRAINT'附近的語法不正確

Question

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消息156，15級，狀態1，行20
關鍵字“CONSTRAINT”附近的語法不正確。

我完成了我的研究，但我仍然堅持完成這個腳本。

這就是我輸入的內容。

DROP TABLE SEMESTER; 
DROP TABLE CLASS;
DROP TABLE STUDENT;

CREATE TABLE STUDENT (
stuid int not null,
stulname CHAR(40) not null,
stufname CHAR(40) not null,
stugender CHAR(1) not null,
stubirthdate DATE not null);

CREATE TABLE CLASS (
title CHAR(40) not null PRIMARY KEY,
instructor CHAR(40) not null );

CREATE TABLE SEMESTER (
year int not null ); 


CONSTRAINT pk_student PRIMARY KEY (stuid, stulname, stufname, stugender, stubirthdate),
CONSTRAINT pk_class PRIMARY KEY (title, instructor),
CONSTRAINT pk_semester PRIMARY KEY (semid, year)); 

Answer 1

我認為這些CONSTRAINT語句必須是內部 CREATE TABLE語句。 例如， STUDENT表應如下所示：

CREATE TABLE STUDENT (
    stuid int not null,
    stulname CHAR(40) not null,
    stufname CHAR(40) not null,
    stugender CHAR(1) not null,
    stubirthdate DATE not null,
    CONSTRAINT pk_student PRIMARY KEY (stuid, stulname, stufname, stugender, stubirthdate), 
);

否則，RDBMS如何知道每個約束實際屬於哪個表？

Answer 2

DROP TABLE SEMESTER; 
DROP TABLE CLASS;
DROP TABLE STUDENT;

CREATE TABLE STUDENT (
stuid int not null,
stulname CHAR(40) not null,
stufname CHAR(40) not null,
stugender CHAR(1) not null,
stubirthdate DATE not null
CONSTRAINT pk_student PRIMARY KEY (stuid, stulname, stufname, stugender, stubirthdate),);

CREATE TABLE CLASS (
title CHAR(40) not null ,
instructor CHAR(40) not null ,
CONSTRAINT pk_class PRIMARY KEY (title, instructor));

CREATE TABLE SEMESTER (
year int not null ,
semid int not null
CONSTRAINT pk_semester PRIMARY KEY (semid, year));; 

根據我的理解這里約束必須在學生和第二個表的表內創建你在類（標題）上創建2次主鍵並且到第三個表semid本身不在學期表中出現