chapter13-sequence_index.md

数据库对象-序列，索引，同义词

create sequence dept_deptid_seq
increment by 1
start with 1

insert into departments(department_id,
department_name, location_id)
values (dept_deptid_seq.NEXTVAL,
'Support', 2500)

select dept_deptid_seq.CURRVAL
from dual

drop sequence dept_deptid_seq

序列

select *
from user_indexes
where table_owner = 'STUDENT1'

create index emp_last_name_index
on employees(last_name)

select *
from departments
where upper(department_name) = 'SALES'

普通索引 ：对查询没有什么帮助，需要建立函数索引

create index upper_dept_name_index
on departments(upper(department_name))

select *
from departments
where upper(department_name) = 'SALES'

begin
  for i in 1000 .. 9999 loop
    insert into departments values(i, 'Test_department_name', 200, 1700);
  end loop;
end;

create index dept_name_idx on departments(department_name);
drop index dept_name_idx

create index upper_dept_name_idx
on departments(upper(department_name))

函数索引

select * from employees@orcl

create synonym C for employees@orcl

select * from C

drop synonym C

SYNONYM : 同义词