增加约束
LIKE 模糊查询
alter table add constraint check()
alter table dept add constraint fk_ foreign key() reference emp(..)
union --可以插入多条数据
删
delete from ...where
truncate table ..... (清空)
select distinct deptno from emp (消除重复的行)
改
update .... set ... where ...
create sysnonym ....for ...
drop sysnonym....
exp scott/abc file=employ.dmp tables=(emp,dept);
imp sys/abc file=emoploy.dmp fromuser=scott touser=sys commit=y;