如何備份oracle資料庫：
md f:/db_bak/%date:~0,10%
exp userid=bszlhr/bszlhr@orcl_14 file=f:/db_bak/%date:~0,10%/bszlhr%date:~0,10%.dmp log=f:/db_bak/%date:~0,10%/log_bszlhr_%date:~0,10%.log
buffer=64000 owner=bszlhr
-----建立信用資訊的表----------
create table gccredit(
itemid number(10,0),
empid number(10,0),
creditcots varchar2(100),
notes varchar(100)
)select * from gccredit
gcv_credit
-------建立信用資訊的檢視------
create or replace view gcv_credit (
filepath,
unitid,
deptno,
empno,
empname,
position,
itemid,
empid,
creditcots,
notes)as
select emp.filepath ,emp.unitid, emp.deptno, emp.empno, emp.empname,emp.position,
c.itemid,c.empid,c.creditcots,c.notes
from gccredit c, gcemployee emp
where emp.empid = c.empid
select * from gcv_credit
------3.用來查詢資料物件中所包含的字段--------
select * from gc_columns where obj_id in (
select obj_id from gc_dbobjects where obj_class like '%credit%');1.在
oracle
中如何獲取前
10條的記錄：
select * from tablename where rownum<11 order by colname desc 2.
在oracle
中的多表連線查詢，
oracle
多表連線與子查詢
posted on 2009-07-02 13:17 仲巨集偉（
anmo）閱讀
(0) 編輯收藏1
：等值連線
迪卡爾集連線
select ename, a.deptno as a_deptno,b.deptno as b_deptno ,b.dname as
部門from emp a, dept b
等值連線
select ename, a.deptno as a_deptno,b.deptno as b_deptno ,b.dname as
部門from emp a, dept b
where a.deptno = b.deptno; 2
：非等值連線，在
emp表和
salgrade
表中查詢員工的姓名，工資，等級，工資上線，工資下線
select ename as
姓名, sal as
工資, grade as
工資等級
,losal as
工資上線，
hisal as
工資下線
from emp, salgrade
where sal between losal and hisal; 3:
外連右外連
select e.ename, d.dname, e.deptno
from emp e,dept d
where e.deptno = d.deptno(+);
左外連與右外連相反 以
hr登陸查詢表
employees
和departments
表select first_name as
姓名, department_name as
部門名稱
, d.department_id as
部門編號
from employees e, departments d
where e.department_id= d.department_id(+) ; 4:
自連：在同乙個表中查詢每個員工及上司的工號和姓名
select a.empno as
員工編號
, a.ename as
員工姓名
, a.mgr as
上司的員工編號
, b.ename as
上司姓名
from emp a, emp b
where a.mgr = b.empno;
5：sql99
交叉連線
cross join------
相當於迪卡爾集
select e.ename,d.dname
from emp e cross join dept d;
自然連線
natural join------
相當等值連線
select e.ename, d.dname
from emp e natural join dept d;
using
子句-----
使用同名列查詢
select e.ename, d.dname
from emp e join dept d
using (deptno); on
子句------
當列名不同時用
on子句用on
查詢兩張表
select e.ename, d.dname
from emp e join dept d
on e.deptno = d.deptno; 用
on查詢多張表
select e.ename, d.dname
from emp e join dept d
on e.deptno = d.deptno
join
第三個表
on 列
1 = 列2;
內連線（
inner join
）-------
內連線只返回滿足連線條件的資料
select employee_id, last_name, salary, department_id, department_name
from employees inner join departments using(department_id);
左外連select employee_id, last_name, salary, department_id, department_name
from employees left join departments using(department_id);
右外連select employee_id, last_name, salary, department_id, department_name
from employees right join departments using(department_id);
滿外連select employee_id, last_name, salary, department_id, department_name
from employees full outer join departments using(department_id);
子查詢------------
查詢出工資比
scott
高的人select ename, sal from emp
where sal>
(select sal from emp where ename='scott');
查詢那些人和
scott
相同職位的人
select ename, job from emp
where job=
(select job from emp where ename='scott')
and ename <> 'scott';
any的用法< any
意味著小於最大、
> any
大於最小
select empno, ename, sal, job
from emp
where sal
all的用法< all
：小於所有，即小於最小、
> all
：大於所有，即大於最大
select empno, ename, sal, job
from emp
where sal
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