使用循環引用創建表格

Question

如何創建具有循環引用的多個表格。我有這個數據，我想創建在一個鏡頭：

DROP TABLE employee CASCADE CONSTRAINTS; 
CREATE TABLE employee (
    fname varchar2(15) not null, 
    minit varchar2(1), 
    lname varchar2(15) not null, 
    ssn  char(9), 
    bdate date, 
    address varchar2(30), 
    sex  char, 
    salary number(10,2), 
    superssn char(9), 
    dno  number(4), 
    primary key (ssn), 
    foreign key (superssn) references employee(ssn), 
    foreign key (dno) references department(dnumber) 
); 

DROP TABLE department CASCADE CONSTRAINTS; 
CREATE TABLE department (
    dname  varchar2(15) not null, 
    dnumber  number(4), 
    mgrssn  char(9) not null, 
    mgrstartdate date, 
    primary key (dnumber), 
    unique (dname), 
    foreign key (mgrssn) references employee(ssn) 
); 

DROP TABLE dept_locations CASCADE CONSTRAINTS; 
CREATE TABLE dept_locations (
    dnumber number(4), 
    dlocation varchar2(15), 
    primary key (dnumber,dlocation), 
    foreign key (dnumber) references department(dnumber) 
); 

DROP TABLE project CASCADE CONSTRAINTS; 
CREATE TABLE project (
    pname  varchar2(15) not null, 
    pnumber number(4), 
    plocation varchar2(15), 
    dnum  number(4) not null, 
    primary key (pnumber), 
    unique (pname), 
    foreign key (dnum) references department(dnumber) 
); 

DROP TABLE works_on CASCADE CONSTRAINTS; 
CREATE TABLE works_on (
    essn char(9), 
    pno number(4), 
    hours number(4,1), 
    primary key (essn,pno), 
    foreign key (essn) references employee(ssn), 
    foreign key (pno) references project(pnumber) 
); 

DROP TABLE dependent CASCADE CONSTRAINTS; 
CREATE TABLE dependent (
    essn   char(9), 
    dependent_name varchar2(15), 
    sex   char, 
    bdate   date, 
    relationship varchar2(8), 
    primary key (essn,dependent_name), 
    foreign key (essn) references employee(ssn) 
); 

請幫助！

Answer 1

您可以創建的表，然後創建約束：

CREATE TABLE employee (
    fname varchar2(15) not null, 
    minit varchar2(1), 
    lname varchar2(15) not null, 
    ssn  char(9), 
    bdate date, 
    address varchar2(30), 
    sex  char, 
    salary number(10,2), 
    superssn char(9), 
    dno  number(4), 
    primary key (ssn) 
); 

CREATE TABLE department (
    dname  varchar2(15) not null, 
    dnumber  number(4), 
    mgrssn  char(9) not null, 
    mgrstartdate date, 
    primary key (dnumber), 
    unique (dname) 
); 

ALTER TABLE employee ADD CONSTRAINT fk_dno FOREIGN KEY (dno) REFERENCES department(dnumber) DEFERRABLE; 
ALTER TABLE department ADD CONSTRAINT fk_mgrssn FOREIGN KEY (mgrssn) REFERENCES employee(ssn) DEFERRABLE; 

插入時，可以設置延遲的限制，這意味着甲骨文將無法驗證，直到你提交。

ALTER SESSION SET CONSTRAINTS = DEFERRED; 
insert into employee (fname, lname, ssn, dno) values ('Joe','Blow','123456789', 10); 
insert into department(dname, dnumber, mgrssn) values ('Dept1',10, '123456789'); 
commit; 

你也可以設置它們創建它們在最初推遲，但限制必須是「緩徵」在至少做以上。