oracle 建表 练习2

-- Create table
create table COURSE
(
  cno   VARCHAR2(5) not null,
  cname VARCHAR2(20) not null,
  tno   NUMBER not null
)
tablespace USERS
  pctfree 10
  initrans 1
  maxtrans 255
  storage
  (
    initial 64K
    next 1M
    minextents 1
    maxextents unlimited
  );
-- Add comments to the table 
comment on table COURSE
  is ‘课程表‘;
-- Add comments to the columns 
comment on column COURSE.cno
  is ‘课程号（主键）‘;
comment on column COURSE.cname
  is ‘课程名称‘;
comment on column COURSE.tno
  is ‘教工编号（外键）‘;