create table tb(id int identity(1,1),constraint pkid primary key (id)) create table tb(id int identity(1,1) primary key )
3.已經建好一數據表，里面有字段id，將id設為主鍵
復制代碼 代碼如下:
alter table tb alter column id int not null alter table tb add constraint pkid primary key (id)
4.刪除主鍵
復制代碼 代碼如下:
Declare @Pk varChar(100); Select @Pk=Name from sysobjects where Parent_Obj=OBJECT_ID('tb') and xtype='PK'; if @Pk is not null exec('Alter table tb Drop '+ @Pk)
