方法1-show parameter
方法2-V$Parameter
V$Parameter和Show Parameter的区别
V$Parameter能得到更多的信息，但show parameter更简单而且它会自动完成“通配”
如何修改数据库的parameter
-- MEMORY - This affects the database now; but will not remain after a restart.
-- SPfile - This does not change the instance immediately, but will modify the SPfile takes effect after a restart.
-- BOTH - change both the current instance and the spfile.