har dict mit 應用 left user span varchar2 style

select * from user1

select * from dicts

-- 多對一（字典類應用）

drop table user1;

create table user1(

id varchar2(10),

username varchar2(20),

sex varchar2(10),

minzu varchar2(10)

);

insert into user1 values(1,‘小明‘,‘男‘,‘漢族‘);

insert into user1 values(1,‘小芳‘,‘女‘,‘傣族‘);

commit;

select * from user1

<option value="0">男</option>

<option value="1">女</option>

-----------------------------

drop table user1;

create table user1(

id varchar2(10) primary key,

user_name varchar2(20),

sex number(1),

minzu number(2)

);

insert into user1 values(1,‘小明‘,1,1);

insert into user1 values(2,‘小芳‘,0,2);

commit

select * from user1

drop table dicts

create table dicts(

id number primary key,

display varchar2(100), -- 顯示內容

key_value number, -- 真實的值

key_type varchar2(10), -- 類別

lang varchar2(10) -- 語言

);

insert into dicts values(1,‘男‘,1,‘sex‘,‘cn‘);

insert into dicts values(2,‘女‘,0,‘sex‘,‘cn‘);

insert into dicts values(3,‘boy‘,1,‘sex‘,‘en‘);

insert into dicts values(4,‘girl‘,0,‘sex‘,‘en‘);

insert into dicts values(5,‘漢族‘,1,‘minzu‘,‘cn‘);

insert into dicts values(6,‘傣族‘,2,‘minzu‘,‘cn‘);

insert into dicts values(7,‘hanzu‘,1,‘minzu‘,‘en‘);

insert into dicts values(8,‘daizu‘,2,‘minzu‘,‘en‘);

select * from dicts

-- 傳統的關聯方式

select

user1.id,

user_name,

dict_sex.display sex,--sex,

dict_minzu.display minzu--minzu

from user1,dicts dict_sex,dicts dict_minzu

where

user1.sex=dict_sex.key_value and dict_sex.key_type=‘sex‘ and dict_sex.lang=‘en‘

and

user1.minzu=dict_minzu.key_value and dict_minzu.key_type=‘minzu‘ and dict_minzu.lang=‘en‘

-- 傳統的關聯方式2

select * from user1

select * from dicts where lang=‘cn‘ and key_type=‘sex‘

select * from dicts where lang=‘cn‘ and key_type=‘minzu‘

select user1.id,user_name,dict1.display sex,dict2.display minzu from

user1,

(select * from dicts where lang=‘cn‘ and key_type=‘sex‘) dict1,

(select * from dicts where lang=‘cn‘ and key_type=‘minzu‘) dict2

where

user1.sex=dict1.key_value

and

user1.minzu=dict2.key_value

-- 優化

select user1.id,user_name,dict1.display sex,dict2.display minzu

from user1

left join

(select * from dicts where lang=‘cn‘ and key_type=‘sex‘) dict1

on

user1.sex=dict1.key_value

left join

(select * from dicts where lang=‘cn‘ and key_type=‘minzu‘) dict2

on

user1.minzu=dict2.key_value

-- 實驗

select * from user1

insert into user1 values(4,‘小紅‘,2,1);

insert into user1 values(5,‘小林‘,1,3);

commit

-- 觀察內關聯的結果

（小紅和小林都丟了）

-- 觀察左關聯的結果

-- 繼續對右表操作

select * from dicts

insert into dicts values(9,‘外星族‘,99,‘minzu‘,‘cn‘);

commit

select ‘‘ from dual
select null from dual
select nvl(‘123‘,‘未知‘) from dual
select nvl(null,‘未知‘) from dual

select * from dicts
insert into dicts values(10,‘維吾爾族‘,3,‘minzu‘,‘cn‘)
commit

ORACLE1.11 - 多對一