添加外鍵失敗，大家?guī)兔匆幌履睦锍鲥e了？
CREATE TABLE student(
sid INT PRIMARY KEY,
sname VARCHAR(20) NOT NULL,
sex CHAR(2),CONSTRAINT fk_stu_gid FOREIGN ?KEY(gid)
REFERENCES grade(gid);)
CREATE TABLE student(
sid INT PRIMARY KEY,
sname VARCHAR(20) NOT NULL,
sex CHAR(2),
gid INT
ALTER TABLE student ADD
CONSTRAINT fk_stu_gid FOREIGN ?KEY(gid)
REFERENCES grade(gid);
2016-09-23
把我敲得分享給你
create table grade
(
gid int primary key;
gname varchar(20) not null;
gdesc varchar(50)?
);
create table students
(
sid int primary key;
sname varchar(20) not null;
sex char(2),
gid int?
);
alter table students add constraint fk_students_gid foreign key (gid)
references grade(gid);