bamazon

An Amazon-like storefront usingNode.js for the Command Line Interface and MySQL for the database. The app will take in orders from customers and deplete stock from the store's inventory.

Getting Started

The following framework and packages are required to get the project up and running on your local machine for development and testing purposes.

Technology Used

• Node.js
• MySQL database
• MySQL module Node module is a driver for MySQL.
• Inquirer module Node module prompts the user. A command line interface (CLI)
• CLI table module Node module for formatting tables in the console.
• Colors module Node module for adding color.

Installation

Download the repo using the git clone command in your terminal

Running the applications

Within your terminal, you can run the following commands for each role:

Customer Storefront App:

• node bamazonCustomer.js

Manager App:

• node bamazonManager.js

Supervisor App:

• node bamazonSupervisor.js

SQL Schema and Seeds for the product and department table

• SQL Product & Department Table Schema
• Sample Seeds

How the storefront works

bamazonCustomer.js

This program starts with loading the screen with the current list of items available to buy.

User then enters the Item ID and quantity. I made sure to validate each entry so that the ID is valid and a number, and that the quantity greater than 0 and less than or equal to the item's stock quantity.

SQL commands used:

• SELECT * FROM products gets all the products from the product table
• Once the order has been entered, the product table is updated with the following SQL commands:

UPDATE products 
SET stock_quantity = stock_quantity - ?, product_sales = product_sales + ( price * ? ) 
WHERE item_id = ?

bamazonManager.js

The Manager program starts with 4 choices: * View Products for Sale * View Low Inventory (of less than 5) * Update Inventory * Add New Product.

View Products for Sale section:

View Low Inventory section shows all items that have 5 or less stock quantity:

Update Inventory section first shows a list of current items taken from the database table. Then you can add more stock.

Add New Product section lets you first select from a list the current departments available.

Then it asks for a new product name, price, and stock quantity. Then answers are INSERT INTO products table with a primary key automatically generated.

SQL commands used:

• An INNER JOIN and ON products.department_id = departments.department_id was used to join the product and departments table by their IDs.
• CAST() was used to display product_sales in decimal form at two decimal places.
• ORDER BY was used to sort the table by department

SELECT 
item_id, product_name,
departments.department_name AS department,
price,
stock_quantity,
CAST(product_sales AS DECIMAL(6,2)) AS sales 
FROM products
INNER JOIN departments
ON products.department_id = departments.department_id
ORDER BY department

• INSERT INTO products SET product_name, price, department_id is used to add a new product.
• UPDATE products SET stock_quantity = stock_quantity + ? WHERE item_id = ? is used to add stock to existing item.

bamazonSupervisor.js

The Supervisor main menu gives you two choices: View Product Sales by Department and Create a New Department.

The View Product Sales by Department menu lets you choose a department from a paginated list.

Results from the movies department:

Create a New Department asks you to enter a new department name and overhead costs.

SQL commands used

I needed to modify the product table so that each department name was replaced with the correct department_id. I found a way to change it from Stackoverflow - Can I move a column from one table to another...

-- For bamazonSupervisor.js
CREATE TABLE departments (
    department_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    department_name VARCHAR(60),
    over_head_costs DECIMAL(6,2)
);

-- copy from products table to departments table without creating duplicates using SELECT DISTINCT
INSERT INTO departments (department_name) 
SELECT DISTINCT department_name FROM products;

-- Add department_id to products table, which references departments
ALTER TABLE products ADD COLUMN department_id INT, 
    ADD FOREIGN KEY (department_id) REFERENCES departments(department_id);

-- update products table with corresponding department_id, based on JOIN of department_name in both tables. Multi-Table UPDATE is MySQL only syntax.
UPDATE products JOIN departments USING (department_name)
SET products.department_id = departments.department_id;

-- delete redundant department_name from products table.
ALTER TABLE products DROP COLUMN department_name;

To get the total profits, the product and department tables needed to be joined so that the sum of the product sales by department is subtracted by the department overhead.

• SUM(products.product_sales)-departments.over_head_costs AS total_profit

SELECT products.department_id, 
    departments.department_name, 
    departments.over_head_costs, 
    SUM(products.product_sales) AS product_sales, 
    SUM(products.product_sales)-departments.over_head_costs AS total_profit
FROM products 
INNER JOIN departments
ON products.department_id = departments.department_id
WHERE departments.department_id = ?
GROUP BY departments.department_name;

• To add a new department, INSERT INTO is used

Programmer's Notes

• Inquirer can have paginated lists
  • Each item in list can have a value
  • EX: [{name: "item 1, value: 1}]
• Array.prototype.includes() was used to see if an array includes a certain value, returning true or false

Callback workflow

Needed to use lots of callbacks to deal with async issues without installing sync modules. Need to keep track the flow of callbacks.

1. Call sqlQueryCallFunction(callback)
   • Ex: viewProducts(tableGenerator);

Regular Expressions - doesn't work without an npm module

W3Schools .match(regexp)