SQL创建表依赖项

我一直致力于创建表格

下面是我一直在研究的代码，如何使代码在

loan\u type

中工作，以编写上班族或非上班族代码

create table loaner 
(
   loan_id number(5) primary key,
   loan_type VARCHAR2 (16),
   loan_start_date date,
   loan_end_date date,
)

create table office_worker 
(
   worker_id number(5) primary_key,
   loan_id number(5) references loaner(loan_id),
   worker_name varchar2(50)
)

create table nonoffice_worker 
(
   nonworker_id number(5) primary_key,
   loan_id number(5) references loaner(loan_id),
   nonworker_name varchar2(50)
);

commit;

---

不能创建约束来检查现有表结构的约束。通常的做法如下：

create table loaner (
loan_id number(5) primary key,
loan_type VARCHAR2 (16),
loan_start_date date,
loan_end_date date,
constraint loaner_uk unique (loan_id, loan_type)
);

create table office_worker (
worker_id number(5) primary_key,
loan_id number(5),
loan_type VARCHAR2 (16),
worker_name varchar2(50),
constraint office_worker_loaner_fk foreeign key (loan_id, loan_type) references loaner (loan_id, loan_type),
constraint office_worker_loan_type_chk check (loan_type = 'OFFICE')
);

create table nonoffice_worker (
nonworker_id number(5) primary_key,
loan_id number(5),
loan_type VARCHAR2 (16),
nonworker_name varchar2(50),
constraint nonoffice_worker_loaner_fk foreeign key (loan_id, loan_type) references loaner (loan_id, loan_type),
constraint nonoffice_worker_loan_type_chk check (loan_type = 'NONOFFICE')
);

即:

在第一个表的（load_id、loan_type）中创建一个冗余的唯一约束

将loan_类型添加到子类型表中，并基于外键（loan_id，loan_类型）

向每个子类型表添加检查约束，以确保使用正确的贷款类型

---

您还可以向表中添加检查约束，但必须检查“loan_type”列是否仅包含所需的值（

office worker

或

非office worker

），否则这将不起作用：

alter table loaner add (CONSTRAINT chk_loan_type CHECK 
(loan_type='office worker' or loan_type='non office worker'));

---

您是否遇到错误？如果将所有员工都放在一个表中，并且只包含一个名为

is_office

的列，不是更好吗？不，没有错误，办公室员工和非办公室员工的贷款类型不同，因此，我需要的是，如何对借贷者类型是上班族还是非上班族进行检查worker@Matt对不起，忘了给你贴标签了，伙计。他们只是工人之间的区别吗？贷款类型？这似乎很复杂，谢谢你的帮助。这是一个有效的解决方案。我还添加了check约束选项，以防他的表在loan_type列上有rigth值