oracle

1、查询oracle的连接数2select count(*) from v$session;32、查询oracle的并发连接数4select count(*) from v$session where status='ACTIVE';53、查看不同用户的连接数6select username,count(username) from v$session where username is not null group by username;74、查看所有用户：8select * from all_users;95、查看用户或角色系统权限(直接赋值给用户或角色的系统权限)：10select * from dba_sys_privs;11select * from user_sys_privs;126、查看角色(只能查看登陆用户拥有的角色)所包含的权限13select * from role_sys_privs;147、查看用户对象权限：15select * from dba_tab_privs;16select * from all_tab_privs;17select * from user_tab_privs;188、查看所有角色：19select * from dba_roles;209、查看用户或角色所拥有的角色：21select * from dba_role_privs;22select * from user_role_privs;2310、查看哪些用户有sysdba或sysoper系统权限(查询时需要相应权限)24select * from V$PWFILE_USERS;select count(*) from v$process --当前的连接数select value from v$parameter where name = 'processes' --数据库允许的最大连接数修改最大连接数:alter system set processes = 300 scope = spfile;重启数据库:shutdown immediate;startup;--查看当前有哪些用户正在使用数据SELECT osuser, a.username,cpu_time/executions/1000000||'s', sql_fulltext,machinefrom v$session a, v$sqlarea bwhere a.sql_address =b.address order by cpu_time/executions desc;select count(*) from v$session #连接数select count(*) from v$session where status='ACTIVE'　#并发连接数show parameter processes #最大连接alter system set processes = value scope = spfile;重启数据库 #修改连接SQL> Select count(*) from v$session where status='ACTIVE' ;COUNT(*)----------20SQL> Select count(*) from v$session;COUNT(*)----------187SQL> show parameter processes;NAME TYPE VALUE------------------------------------ ----------- ----------aq_tm_processes integer 0db_writer_processes integer 1gcs_server_processes integer 0job_queue_processes integer 10log_archive_max_processes integer 2processes integer 450SQL>并发指active,I SEESQL> select count(*) from v$session #连接数SQL> Select count(*) from v$session where status='ACTIVE'　#并发连接数SQL> show parameter processes #最大连接SQL> alter system set processes = value scope = spfile;重启数据库 #修改连接unix 1个用户session 对应一个操作系统 process而 windows体现在线程DBA要定时对数据库的连接情况进行检查，看与数据库建立的会话数目是不是正常，如果建立了过多的连接，会消耗数据库的资源。同时，对一些“挂死”的连接，可能会需要DBA手工进行清理。以下的SQL语句列出当前数据库建立的会话情况:select sid,serial#,username,program,machine,statusfrom v$session;输出结果为:SID SERIAL# USERNAME PROGRAM MACHINE STATUS---- ------- ---------- ----------- --------------- --------1 1 ORACLE.EXE WORK3 ACTIVE2 1 ORACLE.EXE WORK3 ACTIVE3 1 ORACLE.EXE WORK3 ACTIVE4 1 ORACLE.EXE WORK3 ACTIVE5 3 ORACLE.EXE WORK3 ACTIVE6 1 ORACLE.EXE WORK3 ACTIVE7 1 ORACLE.EXE WORK3 ACTIVE8 27 SYS SQLPLUS.EXE WORKGROUP\\WORK3 ACTIVE11 5 DBSNMP dbsnmp.exe WORKGROUP\\WORK3 INACTIVE其中，SID 会话(session)的ID号;SERIAL# 会话的序列号，和SID一起用来唯一标识一个会话;USERNAME 建立该会话的用户名;PROGRAM 这个会话是用什么工具连接到数据库的;STATUS 当前这个会话的状态，ACTIVE表示会话正在执行某些任务，INACTIVE表示当前会话没有执行任何操作;如果DBA要手工断开某个会话，则执行:alter system kill session \'SID,SERIAL#\'sql语句SQL语句如下：SELECT username, machine, program, status, COUNT (machine) AS连接数量FROM v$sessionGROUP BY username, machine, program, statusORDER BY machine;显示结果（每个人的机器上会不同）SCHNEIDER|WORKGROUD\WANGZHENG|TOAD.exe|ACTIVE|1SCHNEIDER|WORKGROUP\597728AA514F49D|sqlplusw.exe|INACTIVE|1|WWW-Q6ZMR2OIU9V|ORACLE.EXE|ACTIVE|8PUBLIC|||INACTIVE|0按主机名查询SELECT COUNT(*) FROM V$SESSION WHERE MACHINE = 'DXMH';      'DXMH'为主机名数据恢复语句create table informationlaw_bak as select * from informationlaw as of TIMESTAMP to_timestamp('20121126 103435','yyyymmdd hh24miss');//按机器名分组查select username,machine,count(username) from v$session where username is not null group by username,machine;