1. 索引

1.1 创建索引

create index index_name on table_name(column1, column2 ...);

1.2 删除索引

drop index index_name;

2. 视图

create view view_name as select ... from ... where ...;

3. 修改表

3.1 主键

alter table student add constraint stu_pk primary key (sno);

alter table student drop constraint stu_pk;

3.2 列是否可空

alter table student modify sname not null;

alter table student modify sname null;

3.3 唯一约束

alter table student add constraint stu_uk unique(sname);

alter tablestudent drop constraint stu_uk;

3.4 外键

create table sc (sno char(7), cno char(10), grade int, foreign key(sno) references student(sno));

4. 数据库用户管理

1. grant 系统权限 to {public|role|username} [with admin option]