查看当前license情况
sql> show parameter license;
name type value
------------------------------------ ----------- ------------------------------
license_max_sessions integer 0
license_max_users integer 0
license_sessions_warning integer 0
查看oracle的最大并发数限制，可是查看v$license视图
v$license视图：
里面记录了oracle最大的并发数以及当前用户的连接数，
官方文档有如下描述：
this view contains information about license limits.
columndatatypedescription
sessions_max
number
maximum number of concurrent user sessions allowed for the instance
sessions_warning
number
warning limit for concurrent user sessions for the instance
sessions_current
number
current number of concurrent user sessions
sessions_highwater
number
highest number of concurrent user sessions since the instance started
users_max
number
maximum number of named users allowed for the database
其实，该试图中的sessions_current就等于select count(*) from v$session where type = 'user'
show parameter license_max_sessions //查看最大并发数，如果是0，则默认是无限制，但如果在
在初始化文件里说明了，，就以初始化文件为主