oracle 數據庫通過一個系統視圖獲得連接信息。
如果不知道表名或者列明查詢表。。。。
select table_name,column_name from dba_tab_columns where column_name like '%DISCOUNT%'
select object_name from user_objects where object_type = 'TABLE' and object_name like '%CREDIT%'
查詢數據庫當前進程的連接數:
select count(*) from v$process;
查看數據庫當前會話的連接數:
elect count(*) from v$session;
查看數據庫的併發連接數:
select count(*) from v$session where status='ACTIVE';
查看當前數據庫建立的會話情況:
select sid,serial#,username,program,machine,status from v$session;
查詢數據庫允許的最大連接數:
select value from v$parameter where name = 'processes';
或者:show parameter processes;
修改數據庫允許的最大連接數:
alter system set processes = 300 scope = spfile;
(需要重啓數據庫才能實現連接數的修改)
重啓數據庫:
shutdown immediate;
startup;
查看當前有哪些用戶正在使用數據:
select osuser,a.username,cpu_time/executions/1000000||'s',sql_fulltext,machine
from v$session a,v$sqlarea b
where a.sql_address = b.address
order by cpu_time/executions desc;
備註:UNIX 1個用戶session對應一個操作系統process,而Windows體現在線程。
啓動oracle
su - oracle
sqlplus system/pwd as sysdba //進入sql
startup //啓動數據庫
lsnrctl start //啓動監聽
sqlplus "/as sysdba"
shutdown immediate;
startup mount;
alter database open;