1、主键和外键需要写在子段定义的最后面
2、主键:primary key(字段)
外键:(foreign key(字段) references 表(字段))
CREATE TABLE T_ Department (FId VARCHAR (20),FName VARCHAR (20),FLevel INT, PRIMARY KEY (FId))
CREATE TABLE T_ student (FId VARCHAR (20),FName VARCHAR (20),FLevel INT, foreign key(numid) references T_department (fid))