1、查詢oracle的連接數select count(*) from v$session;2、查詢oracle的并發連接數select count(*) from v$session where status='ACTIVE';3、查看不同用戶的連接數select username,count(username) from v$session where username is not null group by username;4、查看所有用戶：select * from all_users;5、查看用戶或角色系統權限(直接賦值給用戶或角色的系統權限)：select * from dba_sys_privs;select * from user_sys_privs;6、查看角色(只能查看登陸用戶擁有的角色)所包含的權限select * from role_sys_privs;7、查看用戶對象權限：select * from dba_tab_privs;select * from all_tab_privs;select * from user_tab_privs;8、查看所有角色：select * from dba_roles;9、查看用戶或角色所擁有的角色：select * from dba_role_privs;select * from user_role_privs;10、查看哪些用戶有sysdba或sysoper系統權限(查詢時需要相應權限)select * from V$PWFILE_USERS;當前連接數：select count(*) from v$session;最大連接數：select value from v$parameter where name = 'processes'; ? ? ?修改最大連接數: ? ? ?alter system set processes = 300 scope = spfile; ? ? ?重啟數據庫:shutdown immediate;startup;