REF與對象的關係型數據庫查詢

Question

所以目前我的數據庫的內容如下：

//branch table 
create type branch_Type as object(bID number(6), branch_id ref branch_Type, b_street varchar2(20), b_city varchar2(20), b_p_code varchar2(8), b_bPhone number(14)); 

create table branch of branch_Type; 

INSERT INTO branch VALUES(branch_Type('901', NULL, 'Market', 'Edinburgh', 'EH5 1AB', '01311235560')); 

INSERT INTO branch VALUES(branch_Type('908', NULL, 'Bridge', 'Glasgow', 'G18 1QQ', '01413214556')); 

insert into branch SELECT branch_Type('901', ref(e), b_street, b_city, b_p_code, b_bPhone) from branch e where e.BID = '901'; 

insert into branch SELECT branch_Type('908', ref(e), b_street, b_city, b_p_code, b_bPhone) from branch e where e.BID = '908'; 

//employee table 
create type employee_Type as object(e_bid ref branch_Type, empID number(8), e_street varchar2(20), e_city varchar2(20), e_p_code varchar2(8), e_title varchar2(4), e_firstname_surname varchar2(20), emphomephone number(14), emp_mobile_1_2 number(22), supervisorID number(6), e_position varchar2(20), salary number(5), e_ninum varchar2(8), joindate date); 

create table employee of employee_Type; 

insert into employee select ref(e), '101', 'Dart', 'Edinburgh', 'EH1 05T', 'Mrs', 'Alison Smith', '01312125555', '0770562344307907812345', NULL, 'Head', '50000', 'NI001', '01-FEB-06' 
from branch e where e.bid = '901'; 

insert into employee select ref(e), '105', 'New', 'Edinburgh', 'EH2 4AB', 'Mr', 'John William', 01312031990, 07902314551077, '101', 'Manager', '40000', 'NI010', '04-MAR-07' 
from branch e where e.bid = '901'; 

insert into employee select ref(e), '108', 'Old', 'Edinburgh', 'EH9 4BB', 'Mr', 'Mark Slack', 01312102211, NULL, '105', 'accountant', '30000', 'NI120', '01-Feb-09' 
from branch e where e.bid = 901; 

insert into employee select ref(e), '804', 'Adam', 'Edinburgh', 'EH1 6EA', 'Mr', 'Jack Smith', 01311112223, 0781209890, '801', 'Leader', '35000', 'NI810', '05-Feb-08' 
from branch e where e.bid = 908; 

select e_bid from EMPLOYEE where e_bid = '901'; //query I'm using 

我想查詢員工表中被引用到分支表，但投標的，當我運行工作表腳本輸出告訴我，我沒有選擇行。

Answer 1

e_bid是對分支對象的引用，並且不引用對象中包含的bID列。你想：

SELECT e_bid 
FROM EMPLOYEE 
WHERE DEREF(e_bid).bID = 901; 

我看不出爲什麼你BRANCH_TYPE需要包含一個自我參考（當你設置要創建的分支的重複這樣就會有一個實例，其中branch_id是NULL而另一種它是指自己）。

您是通過表中的重複幾個結構和更好的結構可能是：

DROP SEQUENCE EMPLOYEES__ID__SEQ; 
DROP TABLE EMPLOYEES; 
--DROP TYPE EMPLOYEE_TYPE; 
--DROP TABLE BRANCHES; 
--DROP TYPE BRANCH_TYPE; 
--DROP TYPE PHONENUMBER_TABLE_TYPE; 
--DROP TYPE PHONENUMBER_TYPE; 
--DROP TYPE ADDRESS_TYPE; 

CREATE TYPE ADDRESS_TYPE AS OBJECT(
    street varchar2(20), 
    city varchar2(20), 
    p_code varchar2(8) 
); 
/

CREATE TYPE PHONENUMBER_TYPE AS OBJECT(
    international varchar2(4), 
    area   varchar2(5), 
    local   varchar2(8) 
); 
/

CREATE TYPE PHONENUMBER_TABLE_TYPE AS TABLE OF PHONENUMBER_TYPE; 
/

CREATE TYPE BRANCH_TYPE AS OBJECT (
    ID  number(6), 
    Address ADDRESS_TYPE, 
    Phone PHONENUMBER_TYPE 
); 
/

create table branches of branch_type(ID PRIMARY KEY); 

INSERT INTO BRANCHES VALUES (
    901, 
    ADDRESS_TYPE('Market', 'Edinburgh', 'EH5 1AB'), 
    PHONENUMBER_TYPE('044', '1311', '235560') 
); 

INSERT INTO BRANCHES VALUES (
    908, 
    ADDRESS_TYPE('Bridge', 'Glasgow', 'G18 1QQ'), 
    PHONENUMBER_TYPE('044', '1413', '214556') 
); 

create type employee_Type as object(
    branch   ref branch_type, 
    ID    number(8), 
    address   ADDRESS_TYPE, 
    title    varchar2(4), 
    firstname_surname varchar2(20), 
    homephone   PHONENUMBER_TYPE, 
    mobiles   PHONENUMBER_TABLE_TYPE, 
    supervisor  REF EMPLOYEE_TYPE, -- Change this to a REF 
    position   varchar2(20), 
    salary   number(5), 
    ninum    varchar2(8), 
    joindate   date 
); 
/

create table employees of employee_Type (
    ID PRIMARY KEY 
) NESTED TABLE mobiles STORE AS employees_mobiles; 

CREATE SEQUENCE employees__id__seq; 

insert into employees 
select ref(b), 
     101, -- EMPLOYEES__ID__SEQ.NEXTVAL, 
     ADDRESS_TYPE('Dart', 'Edinburgh', 'EH1 05T'), 
     'Mrs', 
     'Alison Smith', 
     PHONENUMBER_TYPE('044', '1312', '125555'), 
     PHONENUMBER_TABLE_TYPE(
     PHONENUMBER_TYPE('044', '7705', '623443'), 
     PHONENUMBER_TYPE('044', '7907', '812345') 
     ), 
     NULL, 
     'Head', 
     50000, 
     'NI001', 
     DATE '1906-02-01' 
from branches b 
where b.id = 901; 

insert into employees 
select ref(b), 
     102, -- EMPLOYEES__ID__SEQ.NEXTVAL, 
     ADDRESS_TYPE('New', 'Edinburgh', 'EH2 4AB'), 
     'Mr', 
     'John William', 
     PHONENUMBER_TYPE(NULL, '0131', '2031990'), 
     PHONENUMBER_TABLE_TYPE (PHONENUMBER_TYPE('44', '07902', '314551'), PHONENUMBER_TYPE('44', '07701', '234567')), 
     REF(s), 
     'Manager', 
     40000, 
     'NI010', 
     DATE '2007-03-04' 
from branches b, 
     employees s 
where b.id = 901 
and s.id = 101;