1.增加主键
alter table TABLE_NAME add constraint KEY_NAME primary key (TABLE_COLUMN);
指定表空间
alter table TABLE_NAME add constraint KEY_NAME primary key (TABLE_COLUMN) using index tablespace TABLE_SPACE_NAME;
2.增加外键
alter table TABLE_NAME add constraint FK_NAME foreign key (TABLE_COLUMN) references KEY_TABLE_NAME;
3.使主键或外键失效、生效
alter table TABLE_NAME disable(enable) constraint KEY_NAME;
4、查看各种约束
select constraint_name,table_name,constraint_type,status from user_constraints;
select constraint_name, constraint_type,search_condition, r_constraint_name from user_constraints where table_name = upper('&table_name')

select c.constraint_name,c.constraint_type,cc.column_name
from user_constraints c,user_cons_columns cc
where c.owner = upper('&table_owner') and c.table_name = upper('&table_name')
and c.owner = cc.owner and c.constraint_name = cc.constraint_name
order by cc.position;

5、删除主键或外键
alter table TABLE_NAME drop constraint KEY_NAME;
6、建外键
单字段时：create table 表名 (col1 char(8),
cno char(4) REFERENCE course);
多个字段时,在最后加上 Foreign Key (字段名) REFERENCE 表名(字段)
连带删除选项 (on delete cascade
当指定时，如果父表中的记录被删除，则依赖于父表的记录也被删除
REFERENCE 表名（） on delete cascade;
7、删除带约束的表
Drop table 表名 cascade constraints;

8：索引管理
<1>.creating function-based indexes
sql> create index summit.item_quantity on summit.item(quantity-quantity_shipped);

<2>.create a B-tree index
sql> create [unique] index index_name on table_name(column,.. asc/desc) tablespace
sql> tablespace_name [pctfree integer] [initrans integer] [maxtrans integer]
sql> [logging | nologging] [nosort] storage(initial 200k next 200k pctincrease 0
sql> maxextents 50);

<3>.pctfree(index)=(maximum number of rows-initial number of rows)*100/maximum number of rows

<4>.creating reverse key indexes
sql> create unique index xay_id on xay(a) reverse pctfree 30 storage(initial 200k
sql> next 200k pctincrease 0 maxextents 50) tablespace indx;

<5>.create bitmap index
sql> create bitmap index xay_id on xay(a) pctfree 30 storage( initial 200k next 200k
sql> pctincrease 0 maxextents 50) tablespace indx;

<6>.change storage parameter of index
sql> alter index xay_id storage (next 400k maxextents 100);

7.allocating index space
sql> alter index xay_id allocate extent(size 200k datafile 'c:/oracle/index.dbf');

<8>.alter index xay_id deallocate unused;

<9>、查看索引
SQL>select index_name,index_type,table_name from user_indexes order by table_name;
<10>、查看索引被索引的字段
SQL>select * from user_ind_columns where index_name=upper('&index_name');

11、创建序列
select * from user_sequences;
create sequence SEQ_NAME start with 1000
maxvalue 1000 increment by 1;
alter sequence SEQ_NAME minvalue 50 maxvalue 100;
12、删除重复行
update a set aa=null where aa is not null;

delete from a where rowid!=
(select max(rowid) from a b where a.aa=b.aa);
13、删除同其他表相同的行
delete from a where exits
(select 'X' from b where b.no=a.no);
或
delete from a where no in (select no from b);
14、查询从多少行到多少行的记录(可以用在web开发中的分页显示)

select * from ( select rownum row_id,b.* from (select a.* from sys_oper a) b )
where row_id between 15 and 20

15、对公共授予访问权
grant select on 表名 to public;
create public synonym 同义词名 for 表名;
16、填加注释
comment on table 表名 is '注释';
comment on column 表名.列名 is '注释';
17、分布式数据库,创建数据库链路
create [public] database link LINKNAME
[connect to USERNAME identified by PASSWORD]
[using 'CONNECT_STRING']
可以在服务器端，也可以在客户端建立，但必须注意，两台服务器之间
数据库必须可以互访，必须各有各自的别名数据库
18、查看数据库链路
select * from all_db_links;
select * from user_db_links;
查询 select * from TABLENAME@DBLNKNAME;
创建远程数据库同义词
create synonym for TABLENAME@DBLNKNAME;
操纵远程数据库记录
insert