Having two different Customer Types in a Database - sql

Question

My system needs two different Customer Types. I need an Individual and Corporate Customer. How would I go about creating the tables in Apex?
Do I need a Customer, Individual and Corporate table or just a Customer and Corporate table?
This system is for a Car Hire.
The attributes I would need are: Customer ID, First Name, Surname, Address, Post Code, Phone Number, Corporate Name, Frequency (this is for the Corporate entity based on how regularly they hire).

Answer 1

A corporation name belongs to the corporation not to an individual customer; so create a Corporations table and then reference that in a foreign key for your corporate customers. You can also separate out the core Customer data from the CorporateCustomer data and store these in separate tables:
Oracle 18c Setup:
CREATE TABLE Customers (
id NUMBER(10,0)
GENERATED ALWAYS AS IDENTITY
CONSTRAINT Customers__id__pk PRIMARY KEY,
first_name VARCHAR2(200)
CONSTRAINT Customers__firstname__nn NOT NULL,
surname VARCHAR2(200)
CONSTRAINT Customers__surname__nn NOT NULL,
post_code VARCHAR2(7)
CONSTRAINT Customers__postcode__nn NOT NULL,
phone_number VARCHAR2(15)
CONSTRAINT Customers__phone__nn NOT NULL
);
CREATE TABLE Corporations(
id NUMBER(10,0)
GENERATED ALWAYS AS IDENTITY
CONSTRAINT Corporations__id__pk PRIMARY KEY,
name VARCHAR2(500)
CONSTRAINT Corporations__name__nn NOT NULL
);
CREATE TABLE Corporate_Customers (
id NUMBER(10,0)
CONSTRAINT CorporateCustomers__id__pk PRIMARY KEY
CONSTRAINT CorporateCustomers__id__fk REFERENCES Customers(id),
corporation NUMBER(10,0)
CONSTRAINT CorporateCustomers__corp__nn NOT NULL
CONSTRAINT CorporateCustomers__corp__fk REFERENCES Corporations(id),
frequency NUMBER(10,0)
CONSTRAINT CorporateCustomers__freq__nn NOT NULL
CONSTRAINT CorporateCustomers__freq_gte_0__chk CHECK ( frequency >= 0 )
);
db<>fiddle