创建别名：
create alias alias_name for tab_name|view_name...
删除别名：
drop alias alias_name
创建同义词（synonym）：
create synonym syn_name for ...
create public synonym syn_name for ...
删除同义词：
drop synonym syn_name
drop public synonym syn_name
创建别名：
create alias alias_name for tab_name|view_name...
删除别名：
drop alias alias_name
创建同义词（synonym）：
create synonym syn_name for ...
create public synonym syn_name for ...
删除同义词：
drop synonym syn_name
drop public synonym syn_name