-- 子查询-- in 等于表中的任意一个select * from Stu where id in (select id from scores)-- 和子查询返回结果中的某一个值比较成立即可select * from scores where id > all (select id from stu )-- 和子查询返回结果中的所有值比较select * from scores where id > any (select id from stu )select * from stu-- 追加一个列或多个列（字段）alter table stu add (age number,address varchar2(5))-- 修改一个列（字段）-- 修改字段的尺寸alter table stu modify (address varchar2(23)) -- 修改字段的数据类型alter table stu modify (address number )-- 删除一个列（字段）alter table stu drop column address -- 删除多列alter table stu drop (age,address)-- 列重命名alter table stu rename column name to lastname-- 清空表truncate table testselect * from testinsert into test (id) values (4)--commit会默认创建节点commitinsert into test (id) values (5)-- 回滚到上一个节点rollback-- 创建指定节点savepoint domeinsert into test (id) values (9)-- 回滚到指定节点rollback to dome