--将列修改不不允许null的,再创建主键就没问题了.alter table tb_author alter column aid int not null alter table tb_author alter column aname varchar(10) not null go alter table tb_author add constraint PK_tb_author primary key(aid,aname)
--或者你在创建表的时候就指定 not null create table tb_author(aid int not null,aname varchar(10) not null) alter table tb_author add constraint PK_tb_author primary key(aid,aname)
alter table tb_author alter column aname varchar(10) not null
go
alter table tb_author add constraint PK_tb_author primary key(aid,aname)
create table tb_author(aid int not null,aname varchar(10) not null)
alter table tb_author add constraint PK_tb_author primary key(aid,aname)