Oracle查看容許的最大鏈接數和當前鏈接數

目前總結的語句，在查看數據的鏈接狀況頗有用 ，寫完程序一邊測試代碼一邊查看數據庫鏈接的釋放狀況有助於分析優化出一個健壯的系統程序來。
1.
Sql代碼
1.select count() from v$process
select count() from v$process --當前的數據庫鏈接數
2.
Sql代碼
1.select value from v$parameter where name = 'processes'
select value from v$parameter where name = 'processes'--數據庫容許的最大鏈接數
3.
Sql代碼
1.alter system set processes = 300 scope = spfile;
alter system set processes = 300 scope = spfile;--修改最大鏈接數:
4.
Sql代碼
1.shutdown immediate;
2.startup;
shutdown immediate;
startup;--重啓數據庫
5.
Sql代碼
1.SELECT osuser, a.username,cpu_time/executions/1000000||'s', b.sql_text,machine
2.from v$session a, v$sqlarea b
3.where a.sql_address =b.address order by cpu_time/executions desc;
SELECT osuser, a.username,cpu_time/executions/1000000||'s', b.sql_text,machine
from v$session a, v$sqlarea b
where a.sql_address =b.address order by cpu_time/executions desc;
--查看當前有哪些用戶正在使用數據
6.
Sql代碼
1.select count() from v$session
select count() from v$session --當前的session鏈接數
7.
Sql代碼
1.select count() from v$session where status='ACTIVE'
select count() from v$session where status='ACTIVE'　--併發鏈接數
8.
Sql代碼
1.show parameter processes
show parameter processes --最大鏈接
9.
Sql代碼
1.alter system set processes = value scope = spfile;