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 ;