关于oracle常用语句的一些整理

表的别名平级，里层用 列的别名外层用(分组是) 排序却不是
left join 一对多和多对一情况
数据库名    表空间，实例名    用户名密码

alter table EP_CTI_CDR  add primary key (ID)alter table uc_system_user add foreign key (dept_id) references uc_system_role (id)ALTER TABLE ep_cti_agentADD UNIQUE (agname)alter table uc_system_user add constraint username_unique unique(username)create sequence seq_a minvalue 1 maxvalue 99999999 start with 1 increment by 1 cache 20;create or replace trigger uca_trigger before insert on uc_call_agent for each rowbegin select seq_a.nextval into:new.id from dual;end;group by order by 别名