Duplicate Entry for Primary Key - mysql

Question

The task given is:
Create a new relational table to store information about the company names of all suppliers and the total number of products supplied by each supplier. Enforce, the appropriate consistencyconstraints on the new table. Next, copy into the new table information about the company names of all suppliers and the total number of products supplied by each supplier.
I'm recieving an error Duplicate Entry for key "PRIMARY" When i try and run this script
CREATE TABLE COMPANY_AND_SUPPLIERS (
COMPANY_NAME VARCHAR (40) NOT NULL DEFAULT 'EMPTY',
PRODUCT_NAME VARCHAR(40) NOT NULL DEFAULT 'EMPTY' ,
TOTAL_PRODUCTS VARCHAR(40) NOT NULL DEFAULT 'EMPTY',
CONSTRAINT SUPPLIER_PKEY PRIMARY KEY(COMPANY_NAME) ,
CONSTRAINT SUPPLIER_FKEY FOREIGN KEY (COMPANY_NAME) REFERENCES SUPPLIER(COMPANY_NAME)
);
INSERT INTO COMPANY_AND_SUPPLIERS(COMPANY_NAME, PRODUCT_NAME)
SELECT DISTINCT SUPPLIER.COMPANY_NAME, PRODUCT.PRODUCT_NAME
FROM SUPPLIER, PRODUCT;
UPDATE COMPANY_AND_SUPPLIERS
SET TOTAL_PRODUCTS = (SELECT COUNT(*) AS TOTALPRODUCTS
FROM PRODUCT);
The Whole purpose of the exercise is to copy company names of all suppliers and the total number of products supplied by each supplier.
TABLES GIVEN
CREATE TABLE SUPPLIER
(
COMPANY_NAME VARCHAR(40) NOT NULL,
CONTACT_NAME VARCHAR(30),
CONTACT_TITLE VARCHAR(30),
ADDRESS VARCHAR(60),
CITY VARCHAR(15),
REGION VARCHAR(15),
POSTAL_CODE VARCHAR(10),
COUNTRY VARCHAR(15),
PHONE VARCHAR(24),
FAX VARCHAR(24),
HOME_PAGE VARCHAR(500),
CONSTRAINT PK_SUPPLIER PRIMARY KEY (COMPANY_NAME)
);
CREATE TABLE PRODUCT
(
PRODUCT_NAME VARCHAR(40) NOT NULL,
SUPPLIER_NAME VARCHAR(40) NOT NULL,
CATEGORY_NAME VARCHAR(30) NOT NULL,
QUANTITY_PER_UNIT VARCHAR(20),
UNIT_PRICE DECIMAL(10,2) NOT NULL DEFAULT 0,
UNITS_IN_STOCK DECIMAL(9) NOT NULL DEFAULT 0,
UNITS_ON_ORDER DECIMAL(9) NOT NULL DEFAULT 0,
REORDER_LEVEL DECIMAL(9) NOT NULL DEFAULT 0,
DISCONTINUED CHAR(1) NOT NULL DEFAULT 'N',
CONSTRAINT PK_PRODUCT PRIMARY KEY (PRODUCT_NAME),
CONSTRAINT FK_CATEGORY_NAME FOREIGN KEY (CATEGORY_NAME) REFERENCES CATEGORY(CATEGORY_NAME),
CONSTRAINT FK_SUPPLIER_NAME FOREIGN KEY (SUPPLIER_NAME) REFERENCES SUPPLIER(COMPANY_NAME),
CONSTRAINT CK_PRODUCT_UNIT_PRICE CHECK (UNIT_PRICE >= 0),
CONSTRAINT CK_PRODUCT_UNITS_IN_STOCK CHECK (UNITS_IN_STOCK >= 0),
CONSTRAINT CK_PRODUCT_UNITS_ON_ORDER CHECK (UNITS_ON_ORDER >= 0),
CONSTRAINT CK_PRODUCT_REORDER_LEVEL CHECK (REORDER_LEVEL >= 0),
CONSTRAINT CK_PRODUCT_DISCONTINUED CHECK (DISCONTINUED in ('Y','N'))
);

Answer 1

The column company_name should not be a primary key because a primary key is a unique value.
Take this as an example
If a Database administrator creates a table with first_name as the primary key, it would be a disaster since there are a lot of people who has John as their first name
That is why most of the time, the primary key is a integer, then we make it unique using this method.

Answer 2

Your table isn't supposed to contain the product names, just the company and total products. The PRODUCTS table already has the supplier names in it for each product. So you just need to count the number of products for each supplier from that table.
CREATE TABLE Company_Totals (
Company_name VARCHAR(40) NOT NULL,
Total_Products INT(11) NOT NULL,
PRIMARY KEY (Company_name),
FOREIGN KEY (Company_name) REFERENCES Supplier(Company_name)
);
INSERT INTO Company_Totals (Company_name, Total_Products)
SELECT SUPPLIER_NAME, COUNT(*)
FROM PRODUCT
GROUP BY SUPPLIER_NAME;