(Oracle)数据库管理的相关操作语句
2011-11-19 21:40 java线程例子 阅读(174) 评论(0) 编辑 收藏 举报1. 插入( insert )
<1>一次只能插入一行数据
插入部分字段的用法:insert into table_name(column1,column2,column3) values(value1,value2,value3);
插入空值字段的用法:insert into table_name(column1,column2,column3) values(value1,value2,null);
插入全部字段的用法:insert into table_name values(value1,value2,value3);
<2>一次可以插入多行数据
Insert into table_name1 select语句;
2. 修改( update )
修改字段内容的用法:update table_name set column1=new value,column2=new value where字句;
根据其他表修改数据:update table_name set(column1,column2)=(select语句) where字句;
3. 删除( delete )
Delete from table_name where字句; 该命令把被删除的数据标记为unused 并不释放内存。
4. 数据库事务( database transaction )
Commit 数据库事务提交,将变化写入数据库.
Rollback 数据库事务回退,撤销对数据的修改.
Savepoint 创建保存点,用于事务的阶段撤销.
5. 锁( lock )
<1>隐式锁
对同一行数据,第一个会话修改未提交,则第二个会话不能做修改(相当于给这行加了隐式锁).
<2>显式锁
① 锁定行
Select语句 for update;
② 锁定表
共享锁:lock table table_name in share mode;
独占锁:lock table table_name in exclusive mode;
<3>解锁
Commit;
Rollback;
6. 表( table )
<1>创建( create )
① Create table table_name(column1数据类型(宽度) 列级约束, column2 数据类型(宽度) 列级约束, column3 数据类型(宽度) 列级约束,表级约束);
② Create table table_name(column1,column2.column3) as select语句;
<2>重命名( rename )
Rename old_table_name to new_table_name;
<3>注释
① 为表添加注释:comment on table table_name is ‘字符串’;
清除注释:commenton table table_name is ‘’;
② 为列添加注释:comment on column table_name.column_name is ‘字符串’;
清除注释:commenton column table_name.column_name is ‘’;
<4>修改表结构
① 增加列
Alter table table_name add new_column_name 数据类型(宽度) 约束条件;
② 修改列
Alter table table_name modify column_name 数据类型(宽度) 约束条件;
③ 删除列
Alter table table_name drop columncolumn_name;
Alter table table_name drop columncolumn_name cascade constraints;
<5>删除表
Drop table table_name;
Drop table table_name cascade constraints;
<6>清空表
Truncate table table_name; 该命令用来删除表中的全部数据并释放内存,但不删除表,表依然存在。
7. 约束条件
<1>类别
① 主键( primary key )
列级:constraint constraint_name primary key
表级:constraint constraint_name primary key(column_name1, column_name2, column_name3)
② 非空( not null )
Constraint constraint_name not null
③ 唯一( unique )
列级:constraint constraint_name unique
表级:constraint constraint_name unique(column_name1, column_name2, column_name3)
④ 检查( check )
列级:constraint constraint_name check(条件)
表级:constraint constraint_name check(条件1,条件2)
⑤ 外键( foreign key )
子记录存在,不允许删除主记录:constraint constraint_name foreign key(column_name1,column_name2) references table_name(column_name1,column_name2)
子记录存在,删主则删子:constraint constraint_name foreign key(column_name1,column_name2) references table_name(column_name1,column_name2) on delete cascade
子记录存在,删主则空子:constraint constraint_name foreign key(column_name1,column_name2) references table_name(column_name1,column_name2)on delete set null
<2>使约束条件生效和失效
生效:alter table table_name enable constraint constraint_name;
失效:alter table table_name disable constraint constraint_name;
<3>增加约束条件
Alter table table_name add constraint constraint_name 表级约束条件;
<4>删除约束条件
Alter table table_name drop constraint constraint_name;
Alter table table_name drop constraint constraint_name cascade;
8. 视图( view )
<1>创建( create )
有基表:create or replace view view_name(column_name1,column_name2) as select语句;
无基表:create or replace force view view_name(column_name1,column_name2) as select语句; 会报错!
<2>条件
只读视图:create or replace view view_name(column_name1,column_name2) as select语句 with read only;
限制视图:create or replace view view_name(column_name1,column_name2) as select语句 with check option;
<3>删除
Drop view view_name;
9. 索引( index )
唯一索引(默认情况为非唯一):create unique index index_name ontable_name(column_name1,column_name2);
位图索引(默认情况为B*树索引):create bitmap index index_name ontable_name(column_name1,column_name2);
删除索引:drop index index_name;
10. 序列( sequence )
<1>用法
Create sequence sequence_name increment n start with n maxvalue n nocycle nocache;
Create sequence sequence_name increment n start with n nomaxvalue nocycle nocache;
<2>函数
下一个:sequence_name.nextval
当前:sequence_name.currval
<3>删除
Drop sequence sequence_name;
11. 同义词( synonym )
创建:create synonym synonym_name for table_name;
删除:drop synonym synonym_name;
12. 数据字典
<1>查看同义词
Select object_name from user_objects whereobject_type=’SYNONYM’;
<2>查看序列
Select sequence_name,min_value,max_value,increment_by,last_number from user_sequences;
<3>查看索引
Select index_name,index_type from user_indexs where table_name=’EMP’;
<4>查看视图
Select text from user_views where view_name=’ 视图名‘;
<5>查看表
Select object_name from user_objects where object_type=’TABLE’;