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 into TABLENAME@DBLNKNAME (a,b) values (va,vb);
update TABLENAME@DBLNKNAME set a=’this';
delete from TABLENAME@DBLNKNAME;
怎样执行远程的内嵌过程
begin
otherdbpro@to_html(参数);
end;
19、数据库链路用户密码有特殊字符的时候，可以用双引号把密码引起来
create public database link dblink1 connect to db1 identified by “123*456″ using ‘db11′
20.oracle8中扩充了group by rollup和cube的操作。有时候省了你好多功夫的。
<1>下面的语句可以进行总计
select region_code,count(*) from aicbs.acc_woff_notify
group by rollup(region_code);
<2> 对第1个字段小计，最后合计
select region_code,write_status,count(*) from aicbs.acc_woff_notify
group by rollup(region_code,write_status);
———————-
570 0 3
570 1 2
570 5 –此处小计了570的记录
571 0 10
571 1 2
571 12 –此处小计了571的记录
…..
100 –此处有总计
<3> 复合rollup表达式,只做总计
select region_code,write_status,count(*) from aicbs.acc_woff_notify
group by rollup(region_code,write_status);
<4> 对第1个字段小计，再对第2个字段小计，最后合计
select region_code,write_status,count(*) from aicbs.acc_woff_notify
group by cube(region_code,write_status);
———————-
100 –此处有总计
0 60 –对write_status＝0的小计
1 39 –对write_status＝1的小计
3 1 –对write_status＝3的小计
570 5 –此处小计了570的记录
570 0 3
570 1 2
571 12 –此处小计了571的记录
571 0 10
571 1 2
….
<3> 复合cube表达式,只做总计
select region_code,write_status,count(*) from aicbs.acc_woff_notify
group by cube(region_code,write_status);
<4>下面的语句可以按照rollup不同的字段进行小计
select region_code,write_status,count(*) from aicbs.acc_woff_notify
group by region_code,rollup(write_status);
21.查询view的创建语句
sql>set long 1000
sql>select * from user_views where view_name=’MY_VIEW_NAME';
or
sql>select * from all_views where view_name=’MY_VIEW_NAME';
22、去除数据库中特殊字符
<1>.字符串字段中含有”‘”,如果用来组合sql语句，会造成语句不准确。
比如：replace(f1,””,”)
<2>.字符串字段中含有”t n”,如果用来在c或者c＋＋程序中输出到文件，格式无法保证。
比如：replace(f2,’t’,”)
<3>.清除换行和回车
比如: replace(f2,chr(13)||chr(10),”)
23、如何在字符串里加回车或者tab键
在sqlplus中执行
sql>select ‘UserId=1233111’||chr(10)||’AccId=13431’||chr(9)||’AccId2=11111′ from dual;
24、树形查询
create table zj(
bm number(8),
bmmc varchar2(20),
sjbm number(8)
)
insert into zj values(1,’aaa’,0)
insert into zj values(11,’aaa1′,1)
insert into zj values(12,’aaa2′,1)
insert into zj values(111,’aaa11′,11)
insert into zj values(112,’aaa12′,11)
insert into zj values(113,’aaa13′,11)
insert into zj values(121,’aaa21′,12)
insert into zj values(122,’aaa22′,12)
insert into zj values(123,’aaa23′,12)
—
select bm,bmmc,sjbm,level
from zj
start with sjbm=0
connect by prior bm = sjbm
或者
select bm,bmmc,sjbm,level
from zj
start with sjbm=0
connect by sjbm = prior bm
25、快照
create snapshot SNAPSHOT_NAME
[storage (storage parameter)]
[tablespace TABLESPACE_NAME]
[refresh [fastcompleteforce]
[start with START_DATE next NEXT_DATE]
as QUERY;
create snapshot snapshot_to_study as select * from TABLE_NAME@to_study;
创建角色
create role aa identified by aaa;
授权 grant create snapshot,alter snapshot to aaa;
grant aaa to emp;
create snapshot SNAPSHOT_TO_HTML refresh complete start with sysdate next
sysdate+5/(24*60*60) as select * from a@to_html;
删除 drop snapshot snap_to_html
手工刷新快照,(调用DBMS_SNAPSHOT包中的refresh过程)DBMS_SNAPSHOT.refresh(snapshot_name,refresh_type);
begin
DBMS_SNAPSHOT.REFRESH(‘snap_to_html’,’c’);
end;
对所有快照进行刷新
begin
DBMS_SNAPSHOT.REFRESH_ALL;
end;
怎样执行远程的内嵌过程
begin
otherdbpro@to_html(参数);
end;
26、用户管理
create a user: database authentication
sql> create user juncky identified by oracle default tablespace users
sql> temporary tablespace temp quota 10m on data password expire
sql> [account lock|unlock] [profile profilename|default];
<1>.查看当前用户的缺省表空间
SQL>select username,default_tablespace from user_users;
<2>生成用户时指定缺省表空间
create user 用户名 identified by 口令 default tablespace 表空间名;
<3>重新指定用户的缺省表空间
alter user 用户名 default tablespace 表空间名
<4>查看当前用户的角色
SQL>select * from user_role_privs;
<5>查看当前用户的系统权限和表级权限
SQL>select * from user_sys_privs;
SQL>select * from user_tab_privs;
<6>查看用户下所有的表
SQL>select * from user_tables;
<7> alter user语句的quota子句限制用户的磁盘空间
如:alter user jf quota 10M on system;
27、查看放在ORACLE的内存区里的表
SQL>select table_name,cache from user_tables where instr(cache,’Y’)>0;
28、约束条件
create table employee
(empno number(10) primary key,
name varchar2(40) not null,
deptno number(2) default 10,
salary number(7,2) check salary<10000,
birth_date date,
soc_see_num char(9) unique,
foreign key(deptno) references dept.deptno)
tablespace users;
关键字(primary key)必须是非空,表中记录的唯一性
not null 非空约束
default 缺省值约束
check 检查约束,使列的值符合一定的标准范围
unqiue 唯一性约束
foreign key 外部键约束
29、查看创建视图的select语句
SQL>set view_name,text_length from user_views;
SQL>set long 2000; 说明：可以根据视图的text_length值设定set long 的大小
SQL>select text from user_views where view_name=upper(‘&view_name’);
30、查看同义词的名称
SQL>select * from user_synonyms;
31、用Sql语句实现查找一列中第N大值
select * from
(select t.*,dense_rank() over (order by sal) rank from employee)
where rank = N;
32 虚拟自段
<1>. CURRVAL 和 nextval
为表创建序列
CREATE SEQUENCE EMPSEQ … ;
SELECT empseq.currval FROM DUAL ;
自动插入序列的数值
INSERT INTO emp
VALUES (empseq.nextval, ‘LEWIS’, ‘CLERK’,
7902, SYSDATE, 1200, NULL, 20) ;
<2>. ROWNUM
按设定排序的行的序号
SELECT * FROM emp WHERE ROWNUM < 10 ;
<3>. ROWID
返回行的物理地址
SELECT ROWID, ename FROM emp WHERE deptno = 20 ;
33、对CLOB字段进行全文检索
SELECT * FROM A WHERE dbms_lob.instr(a.a,’K’,1,1)>0;
34. 特殊字符的插入，比如”&”
insert into a values (translate (‘at{&}t’,’at{}’,’at’));
35.表管理
<1>.create a table
sql> create table table_name (column datatype,column datatype]….)
sql> tablespace tablespace_name [pctfree integer] [pctused integer]
sql> [initrans integer] [maxtrans integer]
sql> storage(initial 200k next 200k pctincrease 0 maxextents 50)
sql> [logging|nologging] [cache|nocache]
<2>.copy an existing table
sql> create table table_name [logging|nologging] as subquery
<3> create table … as 方式建表的时候，指定表参数
create table a
storage(
initial 1M /*第一次创建时分配空间*/
next 1M /*第一次分配的存储空间用完时在分配*/
)
as select * from b;
<4>.创建临时表
sql> create global temporary table xay_temp as select * from xay;
on commit preserve rows/on commit delete rows
在Oracle中，可以创建以下两种临时表:
a 会话特有的临时表:
create global temporary table () on commit preserve rows;
会话指定，当中断会话时ORACLE将截断表
b 事务特有的临时表:
create global temporary table () on commit delete rows;
事务指定,每次提交后ORACLE将截断表（删除全部行）
c 说明
临时表只在当前连接内有效
临时表不建立索引,所以如果数据量比较大或进行多次查询时,不推荐使用
数据处理比较复杂的时候时表快,反之视图快点
在仅仅查询数据的时候建议用游标: open cursor for ‘sql clause';
<5>
pctfree = (average row size – initial row size) *100 /average row size
pctused = 100-pctfree- (average row size*100/available data space)
<6>.change storage and block utilization parameter
sql> alter table table_name pctfree=30 pctused=50 storage(next 500k
sql> minextents 2 maxextents 100);
<7>.manually allocating extents
sql> alter table table_name allocate extent(size 500k datafile ‘c:/oracle/data.dbf’);
<8>.move tablespace
sql> alter table employee move tablespace users;
<9>.deallocate of unused space
sql> alter table table_name deallocate unused [keep integer]
<10>.drop a column
sql> alter table table_name drop column comments cascade constraints checkpoint 1000;
alter table table_name drop columns continue;
<11>.mark a column as unused
sql> alter table table_name set unused column comments cascade constraints;
alter table table_name drop unused columns checkpoint 1000;
alter table orders drop columns continue checkpoint 1000
data_dictionary : dba_unused_col_tabs
37. 中文是如何排序的？
Oracle9i之前，中文是按照二进制编码进行排序的。
在oracle9i中新增了按照拼音、部首、笔画排序功能。设置NLS_SORT值
SCHINESE_RADICAL_M 按照部首（第一顺序）、笔划（第二顺序）排序
SCHINESE_STROKE_M 按照笔划（第一顺序）、部首（第二顺序）排序
SCHINESE_PINYIN_M 按照拼音排序
38. 数据表中的字段最大数:
表或视图中的最大列数为 1000
39. oracle中的裸设备:
裸设备就是绕过文件系统直接访问的储存空间
40. 在Oracle服务器上通过SQLPLUS查看本机IP地址 ?
select sys_context(‘userenv’,’ip_address’) from dual;
如果是登陆本机数据库，只能返回127.0.0.1
41. 在ORACLE中取毫秒?
9i之前不支持,9i开始有timestamp.
9i可以用select systimestamp from dual;
42. 将N秒转换为时分秒格式？
set serverout on
declare
N number := 1000000;
ret varchar2(100);
begin
ret := trunc(n/3600) || ‘小时’ || to_char(to_date(mod(n,3600),’sssss’),’fmmi”分 “ss”秒”‘) ;
dbms_output.put_line(ret);
end;
43、在某个用户下找所有的索引
select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name
from user_ind_columns, user_indexes
where user_ind_columns.index_name = user_indexes.index_name
and user_ind_columns.table_name = user_indexes.table_name
order by user_indexes.table_type, user_indexes.table_name,
user_indexes.index_name, column_position;
44. not in的替代。
一般not in的效率比较低。特别是数据量大的时候，几乎不能执行。
用下面几种方式可以替换写法
比如要查询在fee_rev_info表中已经销户的用户（不在cm_user中的）(不过下面的例子不是很好，因为bill_id是cm_user的唯一索引）
select * from fee_rev_info where bill_id not in (select bill_id from cm_user)
<1> 用not exists
select * from fee_rev_info a where not exists (select ‘p’ from cm_user b where b.bill_id = a.bill_id)
<2> 用外连接(+)
select a.* from fee_rev_info a,cm_user b
where a.bill_id = b.bill_id (+)
and b.bill_id is null
<3> 用hash_aj
select /*+HASH_AJ*/* from fee_rev_info where bill_id not in (select bill_id from cm_user)
45.怎么样查询特殊字符，如通配符%与_
假如数据库中有表 STATIONTYPE,STATION_571 STATION_572 …
select * from tab where tname like ‘STATION_%’
会显示 STATIONTYPE,STATION_571 … 可以用下面的语句
select * from tab where tname like ‘STATION_%’ escape”
46.如果存在就更新，不存在就插入可以用一个语句实现吗
9i已经支持了，是Merge，但是只支持select子查询，
如果是单条数据记录，可以写作select …. from dual的子查询。
语法为：
MERGE INTO table
USING data_source
ON (condition)
WHEN MATCHED THEN update_clause
WHEN NOT MATCHED THEN insert_clause;
如
MERGE INTO cm_user_credit
USING (select * from dual) ON (user_id =1302514690 )
when MATCHED then update set credit_value = 1000
when NOT MATCHED then insert (user_id,acc_id,bill_id,plan_id,region_code,credit_value) values(1302514690,1305032158,””13857141218””,10070247,””571””,1000);
47.怎么实现一条记录根据条件多表插入
9i以上可以通过Insert all语句完成，仅仅是一个语句，如：
INSERT ALL
WHEN (id=1) THEN
INTO table_1 (id, name)
values(id,name)
WHEN (id=2) THEN
INTO table_2 (id, name)
values(id,name)
ELSE
INTO table_other (id, name)
values(id, name)
SELECT id,name
FROM a;
如果没有条件的话，则完成每个表的插入，如
INSERT ALL
INTO table_1 (id, name)
values(id,name)
INTO table_2 (id, name)
values(id,name)
INTO table_other (id, name)
values(id, name)
SELECT id,name
FROM a;