常用sql语句

计算表的行数count，sh为oracle测试用户，times为该用户下的表

select count(*) from sh.times;

从表student01的B列中，查找不重复的数据

select distinct B from student01;

复制表

create table time_hz tablespace xing1228 as select * from sh.times

将A列的数值加1，但是原始数据库中不变

select a+1,b from student01;

select a,(a+1) bieming,b from student01;

查看当前用户所有表名

select unique tname from col;

查看还没有提交的事务

select * from v$locked_object;

select * from v$transaction;

查看当前所有对象

select * from tab;

查看当前会话的SID和serial

SELECT Sid, Serial#

FROM V$session

WHERE Audsid = Sys_Context('USERENV', 'SESSIONID');

查询当前时间

select to_char(sysdate,'yyyy-mm-dd,hh24:mi:ss') from dual;

使用sqlplus计算

select 256*256 from dual;

通过授权方式来创建用户

grant connect,resource to nlj identified by "123456";

用户之间复制数据
创建一个表dep，dep列不能为空

create table dep (dep number(2) not null, dname char(14), loc char(13));

找出未断开的连接

select process,osuser,username,machine,logon_time ,sql_text

from v$session a,v$sqltext b

where a.sql_address=b.address;

查看表空间名称及大小（MB）

select t.tablespace_name, round(sum(bytes/(1024*1024)),0) ts_size

from dba_tablespaces t, dba_data_files d

where t.tablespace_name = d.tablespace_name

group by t.tablespace_name;

查看表空间对应的物理文件位置及大小

select tablespace_name, file_id, file_name,round(bytes/(1024*1024),0) total_space

from dba_data_files

order by tablespace_name;

查看UNDO段

select segment_name, tablespace_name, r.status,(initial_extent/1024) InitialExtent,(next_extent/1024) NextExtent,max_extents, v.curext CurExtent

From dba_rollback_segs r, v$rollstat v

Where r.segment_id = v.usn(+)

order by segment_name ;

查看表空间使用情况

select sum(bytes)/(1024*1024) as free_space,tablespace_name

from dba_free_space

group by tablespace_name;

查看oracle版本

Select version FROM Product_component_version

Where SUBSTR(PRODUCT,1,6)='Oracle';

查看数据库创建时间和归档方式

Select Created, Log_Mode, Log_Mode From V$Database;

捕捉运行很久的SQL语句（TOP SQL）

select username,sid,opname,

round(sofar*100 / totalwork,0)  '%' as progress,time_remaining,sql_text

from v$session_longops , v$sql

where time_remaining <> 0

and sql_address = address and sql_hash_value = hash_value