--添加列
alter table emp_info add test int;
 
--删除列
alter table emp_info drop column tableid;
 
--重命名表名
exec sp_rename 'calss','class';
 
--重命名列明
exec sp_rename 'class.calssname','classname','COLUMN';
 
--改变列长度
 
alter table emp_info alter column address nchar(100)
 
 
---------------------------------------
–添加约束

–添加主键
alter table student student
add constraint PK_stuNo primary key (studentNO) studentNo --studentNo 列明
 
–添加非空
alter table student
add constraint LoginPwd check (LoginPwd is not null)
 
–默认约束
alter table student
add constraint DF_address default('地址不详') for address;
 
–检查约束
alter table Student
add constraint CK_borndate CHECK(BornDate>='1980-01-01')
 
–唯一约束
alter table student
add constraint UQ_identityCard Unique (identityCard)
 
–外键约束
alter table result
add constraint FK_stuNo foreign key(studentNo) –外键列名
references student(studentNo) –student 主表
–删除约束
alter table student
drop constraint CK_borndate