数据库（mysql oracle）学习小结(二)
salary;
USERS(id,name,birth)
insert into users(id,birth) values(1,to_date('1998-01-01','fmyyyy-mm-dd'));
insert into users values(1,'abc',to_date('1998-01-01','fmyyyy-mm-dd'));
delete users where last_name='zhangsan';
SQL：结构化查询语言,select
DML：数据操纵语言:insert update delete
DCL：数据控制语言:commit rollback。
事务：一组SQL语句的单元（DML语句为主）
DDL：数据定义语言:create table users()
insert into student values(3,'cc',100.99,null);
DDL:数据定义语言
order by
blueuser
blueorder
blue_user
blue_order
oa_user
create table users(
id number(10),
name varchar2(40),
age number(3)
);
alter table users add constaint users_pk primary key (id);
alter table users disable constraint users_pk;
alter table users enable constraint users_pk;
alter table users drop constraint users_pk;
alter table users set unused (name,age);
alter table users et unused column name;
alter table users set unused column age;
alter table users drop unused columns;
drop table users;
rename users to oa_users;
truncate table users;
select e.last_name,e.salary,e.department_id,d.mm from employees e,(select department_id dept_id,max(salary) mm from employees group by department_id) d where e.department_id=d.dept_id;
select dfdfd from A a left outer join (select dfa)
create or relpace view salary_vu
is
select e.last_name,d.department_name,e.salary,j.name from employees e,departments d,job_grades j where e.department_id=d.department_id and e.salary between j.minsalary and j.maxsalary;
SELECT * FROM ( SELECT A.*, ROWNUM RN FROM (SELECT * FROM TABLE_NAME ) A WHERE ROWNUM <= to ) WHERE RN >= from