关系数据库中,当运用 Transact-SQL 语句创建主键时,可以是( )。
A. create table table1 (column1 char(13) not null primary, column2 int not) on primary;
B. alter table table1 with notcheck add constraint [PK_table1] primary key nonclustered ( column1) on primary;
C. alter table table1 column1 primary key ;