1.曾经不小心把开发库的数据库表全部删除,当时吓的要死。结果找到下面的语句恢复到了1个小时之前的数据!很简单。

注意使用管理员登录系统:

select * from 表名 as of timestamp sysdate-1/12   //查询两个小时前的某表数据!既然两小时以前的数据都得到了,继续怎么做,知道了吧。。

 

如果drop了表,怎么办??见下面:

drop table 表名;

数据库误删除表之后恢复:(绝对ok,我就做过这样的事情,汗)不过要记得删除了哪些表名。
flashback table 表名 to before drop;

 

2.查询得到当前数据库中锁,以及解锁:

查锁
SELECT /*+ rule */ s.username,
decode(l.type,'TM','TABLE LOCK',
'TX','ROW LOCK',
NULL) LOCK_LEVEL,
o.owner,o.object_name,o.object_type,
s.sid,s.serial#,s.terminal,s.machine,s.program,s.osuser
FROM v$session s,v$lock l,dba_objects o
WHERE l.sid = s.sid
AND l.id1 = o.object_id(+)
AND s.username is NOT NULL;

解锁
alter system kill session 'sid,serial';
如果解不了。直接倒os下kill进程kill -9 spid

 

3.关于查询数据库用户,权限的相关语句:


 


1.查看所有用户:
select * from dba_user;
select * from all_users;
select * from user_users;


2.查看用户系统权限:
select * from dba_sys_privs;
select * from all_sys_privs;
select * from user_sys_privs;


3.查看用户对象权限:
select * from dba_tab_privs;
select * from all_tab_privs;
select * from user_tab_privs;


4.查看所有角色:
select * from dba_roles;


5.查看用户所拥有的角色:
select * from dba_role_privs;
select * from user_role_privs;

 

4.几个经常用到的oracle视图:注意表名使用大写....................


 


1. 查询oracle中所有用户信息
select * from dba_user;
2. 只查询用户和密码
select username,password from dba_users;
3. 查询当前用户信息
select * from dba_ustats;
4. 查询用户可以访问的视图文本
select * from dba_varrays;
5. 查询数据库中所有视图的文本
select * from dba_views;
6.查询全部索引
select * from user_indexes;
查询全部表格
select * from user_tables;
查询全部约束
select * from user_constraints;
查询全部对象
select * from user_objects;

 

5.查看当前数据库中正在执行的语句,然后可以继续做很多很多事情,例如查询执行计划等等


 


(1).查看相关进程在数据库中的会话   
Select a.sid,a.serial#,a.program, a.status ,
substr(a.machine,1,20), a.terminal,b.spid
from v$session a, v$process b
where a.paddr=b.addr
and b.spid = &spid;

(2).查看数据库中被锁住的对象和相关会话
select a.sid,a.serial#,a.username,a.program,
c.owner, c.object_name
from v$session a, v$locked_object b, all_objects c
where a.sid=b.session_id and
c.object_id = b.object_id;

(3).查看相关会话正在执行的SQL
select sql_text from v$sqlarea where address =
( select sql_address from v$session where sid = &sid );

 

6.查询表的结构:表名大写!!

select t.COLUMN_NAME,
       t.DATA_TYPE,
       nvl(t.DATA_PRECISION, t.DATA_LENGTH),
       nvl(T.DATA_SCALE, 0),
       c.comments
  from all_tab_columns t, user_col_comments c
 whEre t.TABLE_NAME = c.table_name
   and t.COLUMN_NAME = c.column_name
   and t.TABLE_NAME = UPPER('OM_EMPLOYEE_T')
 order by t.COLUMN_ID     

 

7.行列互换:


 



建立一个例子表:
CREATE TABLE t_col_row(
ID INT,
c1 VARCHAR2(10),
c2 VARCHAR2(10),
c3 VARCHAR2(10));
INSERT INTO t_col_row VALUES (1, 'v11', 'v21', 'v31');
INSERT INTO t_col_row VALUES (2, 'v12', 'v22', NULL);
INSERT INTO t_col_row VALUES (3, 'v13', NULL, 'v33');
INSERT INTO t_col_row VALUES (4, NULL, 'v24', 'v34');
INSERT INTO t_col_row VALUES (5, 'v15', NULL, NULL);
INSERT INTO t_col_row VALUES (6, NULL, NULL, 'v35');
INSERT INTO t_col_row VALUES (7, NULL, NULL, NULL);
COMMIT;

下面的是列转行:创建了一个视图
CREATE view v_row_col AS
SELECT id, 'c1' cn, c1 cv
FROM t_col_row
UNION ALL
SELECT id, 'c2' cn, c2 cv
FROM t_col_row
UNION ALL
SELECT id, 'c3' cn, c3 cv FROM t_col_row;

下面是创建了没有空值的一个竖表:
CREATE view v_row_col_notnull AS
SELECT id, 'c1' cn, c1 cv
FROM t_col_row
where c1 is not null
UNION ALL
SELECT id, 'c2' cn, c2 cv
FROM t_col_row
where c2 is not null
UNION ALL
SELECT id, 'c3' cn, c3 cv
FROM t_col_row
where c3 is not null;

  


8.下面可能是dba经常使用的oracle视图吧。呵呵 


 


1.示例:已知hash_value:3111103299,查询sql语句:
select * from v$sqltext
where hashvalue='3111103299'
order by piece
2.查看消耗资源最多的SQL:
SELECT hash_value, executions, buffer_gets, disk_reads, parse_calls
FROM V$SQLAREA
WHERE buffer_gets > 10000000OR disk_reads > 1000000
ORDERBY buffer_gets + 100 * disk_reads DESC;

3.查看某条SQL语句的资源消耗:
SELECT hash_value, buffer_gets, disk_reads, executions, parse_calls
FROM V$SQLAREA
WHERE hash_Value = 228801498AND address = hextoraw('CBD8E4B0');

4.查询sql语句的动态执行计划:
首先使用下面的语句找到语句的在执行计划中的address和hash_code
SELECT sql_text, address, hash_value FROM v$sql t
where (sql_text like '%FUNCTION_T(表名大写!)%')
然后:
SELECT operation, options, object_name, cost FROM v$sql_plan
WHERE address = 'C00000016BD6D248' AND hash_value = 664376056;

5.查询oracle的版本:
select * from v$version;

6.查询数据库的一些参数:
select * from v$parameter

7.查找你的session信息
SELECT SID, OSUSER, USERNAME, MACHINE, PROCESS
FROM V$SESSION WHERE audsid = userenv('SESSIONID');

8.当machine已知的情况下查找session
SELECT SID, OSUSER, USERNAME, MACHINE, TERMINAL
FROM V$SESSION
WHERE terminal = 'pts/tl' AND machine = 'rgmdbs1';

9.查找当前被某个指定session正在运行的sql语句。假设sessionID为100
select b.sql_text
from v$session a,v$sqlarea b
where a.sql_hashvalue=b.hash_value and a.sid=100

 

9.树形结构connect by 排序:


   


查询树形的数据结构,同时对一层里面的数据进行排序
SELECT last_name, employee_id, manager_id, LEVEL
FROM employees
START WITH employee_id = 100
CONNECT BY PRIOR employee_id = manager_id
ORDER SIBLINGS BY last_name;



下面是查询结果
LAST_NAME EMPLOYEE_ID MANAGER_ID LEVEL
------------------------- ----------- ---------- ----------
King 100 1
Cambrault 148 100 2
Bates 172 148 3
Bloom 169 148 3
Fox 170 148 3
Kumar 173 148 3
Ozer 168 148 3
Smith 171 148 3
De Haan 102 100 2
Hunold 103 102 3
Austin 105 103 4
Ernst 104 103 4
Lorentz 107 103 4
Pataballa 106 103 4
Errazuriz 147 100 2
Ande 166 147 3
Banda 167 147 3

 

10.有时候写多了东西,居然还忘记最基本的sql语法,下面全部写出来,基本的oracle语句都在这里可以找到了。是很基础的语句!



1.在数据字典查询约束的相关信息:
SELECT constraint_name, constraint_type,search_condition
FROM user_constraints WHERE table_name = 'EMPLOYEES';
//这里的表名都是大写!
2对表结构进行说明:
desc Tablename
3查看用户下面有哪些表
select table_name from user_tables;
4查看约束在那个列上建立:
SELECT constraint_name, column_name
FROM user_cons_columns
WHERE table_name = 'EMPLOYEES';
10结合变量查找相关某个表中约束的相关列名:
select constraint_name,column_name from user_cons_columns where table_name = '&tablename'
12查询数据字典看中间的元素:
SELECT object_name, object_type
FROM user_objects
WHERE object_name LIKE 'EMP%'
OR object_name LIKE 'DEPT%'
14查询对象类型:
SELECT DISTINCT object_type FROM user_objects ;
17改变对象名:(表名,视图,序列)
rename emp to emp_newTable
18添加表的注释:
COMMENT ON TABLE employees IS 'Employee Information';
20查看视图结构:
describe view_name
23在数据字典中查看视图信息:
select viewe_name,text from user_views
25查看数据字典中的序列:
select * from user_sequences
33得到所有的时区名字信息:
select * from v$timezone_names
34显示对时区‘US/Eastern’的时区偏移量
select TZ_OFFSET('US/Eastern') from DUAL--dual英文意思是‘双重的’
显示当前会话时区中的当前日期和时间:
ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';--修改显示时间的方式的设置
ALTER SESSION SET TIME_ZONE = '-5:0';--修改时区
SELECT SESSIONTIMEZONE, CURRENT_DATE FROM DUAL;--真正有用的语句!
SELECT CURRENT_TIMESTAMP FROM DUAL;--返回的时间是当前日期和时间,含有时区
SELECT CURRENT_TIMESTAMP FROM DUAL;--返回的时间是当前日期和时间,不含有时区!!!
35显示数据库时区和会话时区的值:
select datimezone,sessiontimezone from dual;

13普通的建表语句:
CREATE TABLE dept
(deptno NUMBER(2),
dname VARCHAR2(14),
loc VARCHAR2(13));
15使用子查询建立表:
CREATE TABLE dept80
AS SELECT employee_id, last_name,
salary*12 ANNSAL,
hire_date FROM employees WHERE department_id = 80;
6添加列:// alter table EMP add column (dept_id number(7));错误!!
alter table EMP add (dept_id number(7));
7删除一列:
alter table emp drop column dept_id;
8添加列名同时和约束:
alter table EMP add (dept_id number(7)
constraint my_emp_dept_id_fk references dept(ID));
9改变列://注意约束不能够修改 的!!
alter table dept80 modify(last_name varchar2(30));//这里使用的是modify而不是alter!
24增加一行:
insert into table_name values();

5添加主键:
alter Table EMP add constraint my_emp_id_pk primary key (ID);
11添加一个有check约束的新列:
alter table EMP
add (COMMISSION number(2) constraint emp_commission_ck check(commission>0))
16删除表:
drop table emp;
19创建视图:
CREATE VIEW empvu80
AS SELECT employee_id, last_name, salary
FROM employees WHERE department_id = 80;
21删除视图:
drop view view_name
22找到工资最高的5个人。(top-n分析)(行内视图)
select rownum,employee_id from (select employee_id,salary from
employees order by salary desc)
where rownum<5;
26建立同义词:
create synonym 同义词名 for 原来的名字
或者 create public synonym 同义词名 for 原来的名字
27建立序列:(注意,这里并没有出现说是哪个表里面的序列!!)
CREATE SEQUENCE dept_deptid_seq
INCREMENT BY 10
START WITH 120
MAXVALUE 9999
NOCACHE
NOCYCLE
28使用序列:
insert into dept(ID,NAME) values(DEPT_ID_SEQ.nextval,'Administration');
29建立索引://默认就是nonunique索引,除非使用了关键字:unique
CREATE INDEX emp_last_name_idx ON employees(last_name);
30建立用户:(可能有错,详细查看帮助)
create user username(用户名)
identified by oracle(密码)
default tablespace data01(表空间名//默认存在system表空间里面)
quota 10M(设置大小,最大为unlimited) on 表空间名//必须分配配额!
31创建角色:create ROLE manager
赋予角色权限:grant create table,create view to manage
赋予用户角色:grant manager to DENHAAN,KOCHHAR( 两个用户)
32分配权限:
GRANT update (department_name, location_id)
ON departments
TO scott, manager;
回收权限
REVOKE select, insert
ON departments
FROM scott;
36从时间中提取年,月,日:使用函数extract
select extract(year from sysdate) year,extract(month from sysdate),
extract(day from sysdate) from dual;
37使用函数得到数月之后的日期:to_yminterval(‘01-02’)表示加上1年2月,不能够到天!!
select hire_date,hire_date +to_yminterval('01-02') as hire_date_new from employees where department_id=20
得到多少天之后的日期:直接日期加数字!
select hire_date +3 from employees where department_id=20
38一般的时间函数:
MONTHS_BETWEEN ('01-SEP-95','11-JAN-94')--两个日期之间的月数,返回一个浮点数
ADD_MONTHS ('11-JAN-94',6)--添加月数
NEXT_DAY ('01-SEP-95','FRIDAY') --下一个星期五的日期
LAST_DAY('01-FEB-95')--当月的最后一天!
ROUND(SYSDATE,'MONTH') --四舍五入月
ROUND(SYSDATE ,'YEAR') --四舍五入年
TRUNC(SYSDATE ,'MONTH') --阶段月
TRUNC(SYSDATE ,'YEAR') --截断年
39 group语句:和高级的应用语句:
SELECT department_id, job_id, SUM(salary), COUNT(employee_id) FROM employees
GROUP BY department_id, job_id ;
使用having进行约束:
1.group by rollup:对n列组合得到n+1种情况
SELECT department_id, job_id, SUM(salary) FROM employees WHERE department_id < 60 GROUP BY ROLLUP(department_id, job_id);
2.group by cube:得到2的n次方种情况
SELECT department_id, job_id, SUM(salary) FROM employees WHERE department_id < 60 GROUP BY CUBE (department_id, job_id) ;
3.使用grouping得到一行中构成列的情况,只是返回1和0:是空的话就返回1,否则返回0(注意不要弄反了!)
SELECT department_id DEPTID, job_id JOB, SUM(salary), GROUPING(department_id) GRP_DEPT, GROUPING(job_id) GRP_JOB
FROM employees WHERE department_id < 50 GROUP BY ROLLUP(department_id, job_id);
4.grouping sets:根据需要得到制定的组合情况
SELECT department_id, job_id, manager_id,avg(salary) FROM employees GROUP BY GROUPING SETS ((department_id,job_id), (job_id,manager_id));
40from中使用子查询:返回每个部门中大于改部门平均工资的与员工信息
SELECT a.last_name, a.salary, a.department_id, b.salavg FROM employees a,--下面的地方就是子查询了,主要返回的是一组数据!
(SELECT department_id, AVG(salary) salavg FROM employees GROUP BY department_id) b
WHERE a.department_id = b.department_id
AND a.salary > b.salavg;
41exists语句的使用:
SELECT employee_id, last_name, job_id, department_id
FROM employees outer--下面的 exists里面的select选择出来的是随便的一个字符或者数字都可以
WHERE EXISTS ( SELECT 'X' FROM employees WHERE manager_id = outer.employee_id);
42厉害的with语句:
WITH
dept_costs AS (--定义了一个临时的表
SELECT d.department_name, SUM(e.salary) AS dept_total--其间定义了一个临时的列dept_total
FROM employees e, departments d
WHERE e.department_id = d.department_id
GROUP BY d.department_name),/*注意这里有逗号*/
avg_cost AS (
SELECT SUM(dept_total)/COUNT(*) AS dept_avg
FROM dept_costs)--这里的第二张临时表里面就引用了前面定义的临时表和之间的列!
SELECT * FROM dept_costs WHERE dept_total > (SELECT dept_avg FROM avg_cost) ORDER BY department_name;---最后的查询语句中使用了前面的临时表
43遍历树:
SELECT employee_id, last_name, job_id, manager_id
FROM employees
START WITH employee_id = 101
CONNECT BY PRIOR manager_id = employee_id ;--自底向上的遍历树。

44.更新语句
UPDATE employees SET
job_id = 'SA_MAN', salary = salary + 1000, department_id = 120
WHERE first_name||' '||last_name = 'Douglas Grant';

UPDATE TABLE (SELECT projs
FROM dept d WHERE d.dno = 123) p
SET p.budgets = p.budgets + 1
WHERE p.pno IN (123, 456);

 

11.导入导出dmp文件:

imp 用户名/密码@数据库 ignore=y file=备份文件 log=D:\DBtest\db_bak\imp.log

 

exp system/manager@TEST file=d:\daochu.dmp full=y