Practical Web DataBase Design

This README file presents my hands-on project inspired by the database concepts covered in the book. I've also developed example applications as described in the text. This repository is the result of a collaborative effort during a 6-month mentorship program led by Eng.Ahmed Emad.

Book E-commerce Example

The Entity Relation Diagram Representing The System.

E-Commerce ERD Diagram

Decomposing The Many To Many Relations Into Separate Table.

E-Commerce ERD Decomposed Diagram

A Denormalized Version Of The Diagram

Here is Redundant info, but it offers a Better Performance by avoiding joining many tables.

E-Commerce ERD Denormalized Diagram

Summary of Some Queries and their optimizations

Sample Query	Execution Time Before Optimization	Optimization Technique	Rewritten Query	Execution Time After Optimization
select CATEGORY_ID , count(PRODUCT_ID) as TOTAL_PRODUCTS_NUMBER from product_category pc group by CATEGORY_ID	70.2 ms	Create a composite index on category id and product id for product_category table	-	0.3 ms
select CUSTOMER_ID,CONCAT(c.FIRST_NAME,' ', c.LAST_NAME) as CUSTOMER_NAME, sum(TOTAL_COST) as TOTAL_SPENDING from orders o inner join customer c on c.ID = o.CUSTOMER_ID group by CUSTOMER_ID order by TOTAL_SPENDING desc	147499 ms	Query Rewriting and adding a composite index on cutomer id and total price for orders tables	select CUSTOMER_ID,CONCAT(c.FIRST_NAME,' ', c.LAST_NAME) as CUSTOMER_NAME, TOTAL_SPENDING from (select CUSTOMER_ID, sum(TOTAL_COST) as TOTAL_SPENDING from orders o group by CUSTOMER_ID order by TOTAL_SPENDING desc) o inner join customer c on c.ID = o.CUSTOMER_ID	2120 ms
SELECT o.ID , o.order_date, o.TOTAL_COST , c.id, c.first_name, c.last_name, c.email FROM customer c JOIN orders o ON o.customer_id = c.ID ORDER BY o.order_date DESC LIMIT 1000;	1705 ms	Create an index on order date	-	0.378 ms
select p.NAME from product p where p.QUANTITY < 60	0.0567 ms	Create a composite index on name and quantity	-	0.0262 ms
select c.ID ,c.NAME , sum(p.PRICE) from order_detail od inner join product p on p.ID = od.PRODUCT_ID inner join product_category pc on pc.PRODUCT_ID = p.ID inner join category c on c.ID = pc.CATEGORY_ID group by c.id	8357 ms	Using the denormalized table SALES_HISTORY with covering index	-	5280 ms

Index:

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Hands-on project inspired by the database concepts covered in the book