Staff(员工表):
staffID(员工ID,主键),staffName,sexClassMeeting(班会表):
classMID(班会ID、主键),topic,centent,classMTimeClassMeetingStaffs(与会人员表)
ClassMID,staffID(外键),sign(是否签到),note(备注)请问 ClassMeetingStaffs 表中可以把ClassMID设为主键,又设为外键吗?
建表语句如何写呢?
create table ClassMeetingStaffs
(
classMID varchar(32) primary key foreign key references ClassMeeting(classMID),
sign int ,
note varchar(256)
)
这样写对吗?
staffID(员工ID,主键),staffName,sexClassMeeting(班会表):
classMID(班会ID、主键),topic,centent,classMTimeClassMeetingStaffs(与会人员表)
ClassMID,staffID(外键),sign(是否签到),note(备注)请问 ClassMeetingStaffs 表中可以把ClassMID设为主键,又设为外键吗?
建表语句如何写呢?
create table ClassMeetingStaffs
(
classMID varchar(32) primary key foreign key references ClassMeeting(classMID),
sign int ,
note varchar(256)
)
这样写对吗?
ClassMID是ClassMeeting(班会表)的外键!
create table persons
(id_p int primary key,
lastname varchar(10),
firstname varchar(10),
address varchar(10),
city varchar(10)
)go
create table orders
(
o_id int not null primary key,
orderno int not null,
id_p int,
constraint fk_perorders foreign key (o_id)
references persons(id_p)
)
o_id既是主键 也是外键。