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A beginner's guide to SQL database design

sql
database-design
data-integrity
sql-queries
Nikita BarsukovbyNikita Barsukov·Oct 24, 2024
⚡TLDR

Snack-sized knowledge first: Design an SQL database adopting 3NF (Third Normal Form). It implies distinct tables for separate entities, direct relationships to primary keys, and absolute elimination of transitive dependencies.

-- Users
CREATE TABLE Users (UserID INT PRIMARY KEY, /* Fear no evil, for it's not an email-address PK 🐉*/ 
Username VARCHAR(255), Password VARCHAR(255)); /* "hashed_passwrd123_"...oh, just kidding 🙃 */

-- Products
CREATE TABLE Products (ProductID INT PRIMARY KEY, Name VARCHAR(255), Price DECIMAL(10, 2)); /* For those priceless moments...just kidding, everything has a price 💵 */

-- Orders
CREATE TABLE Orders (OrderID INT PRIMARY KEY, UserID INT, Date DATE, /* Did someone time travel back here from 2038? 🕰️ */
FOREIGN KEY (UserID) REFERENCES Users(UserID)); 

-- OrderItems
CREATE TABLE OrderItems (ItemID INT PRIMARY KEY, OrderID INT, ProductID INT, Quantity INT, 
FOREIGN KEY (OrderID) REFERENCES Orders(OrderID), FOREIGN KEY (ProductID) REFERENCES Products(ProductID)); /* Because, who wants to remember ProductID 1359 from their last order, right? 🤔 */

Aim for descriptive, consistent column names; link tables via primary/foreign keys ensuring relational integrity and mitigating redundancy.

Database design for the long run

Mastering database design for an SQL application isn't just about learning to write code, but about constructing a foundation where your code will be successful and scalable, no matter if it's for a minimalist app or an intricate web platform.

Deciphering relationships

Understanding how to properly model one-to-one, one-to-many, and many-to-many associations will pave the way for designing tables that can interact efficiently, returning logical and optimized results.

Leveraging keys and indexes

Primary keys, acting as unique identifiers—ideally using a surrogate key approach—will boost your efficiency tremendously. Applying indexes on columns featured in WHERE clauses or sorting will turbocharge your queries' performance.

Prioritizing integrity and modularity

One cornerstone of a robust database is data integrity — that's where foreign keys paired with CASCADE DELETE/UPDATE options come into play. Investing in a modular database design will help manage complexity, accounting for potential changes and scalability needs.

Define and track changes

Assign the right data types to columns, maintaining clarity, and striving for efficiency, even if it means micromanaging storage considerations. Incorporate timestamps for tracking data modification and changes - think of it as the "last modified" details on a document.

The flexibility in design

There isn't a "one-size-fits-all" when it comes to database design. Crafting the perfect design hinges on the specific requirements and constraints. Let flexibility and scalability be your mantra throughout the database planning process.

Query writing — an art form

While understanding the structure is crucial, the elegance lies in optimized SQL queries. Practice makes perfect — invest your time in honing your skills to achieve the performance that makes your database stand out.

Drilling into normalization

Normalization—transforming data to minimize redundancy and improve integrity—is a process database designers swear by. Meticulously implementing 3NF (Third Normal Form) will guard against data anomalies.

Tackling many-to-many relationships

Many-to-many relationships can be a bit daunting, but they're broken down to more manageable one-to-many connections using junction tables. This way, the relationships are direct, and connections between data points are captured perfectly!

Considering data security

Don't compromise on data security. Store sensitive information by utilizing hashing and encryption—vital for trustworthiness. Implement roles and permissions to regulate data access.

Bringing in business logic

Sometimes, business rules can be enforced through constraints and triggers. Know when to enable these mechanisms to automate data validation and maintain logical consistency.

Preparing for growth and change

Design your database with future growth in mind. Picture potential schema changes, future requirements, and scalability. A good modular design and decoupling methods can save major overhauls down the line.

explain-codes / Sql / A beginner's guide to SQL database design
Linked

Key value pairs in relational databases

Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc

Do I need to create indexes on foreign keys on Oracle?

Foreign Key to non-primary key

Best practices on primary key, auto-increment, and UUID in SQL databases

Difference between primary key and unique key

Clustered vs Non-Clustered

Database design for the long runDeciphering relationshipsLeveraging keys and indexesPrioritizing integrity and modularityDefine and track changesThe flexibility in designQuery writing — an art formDrilling into normalizationTackling many-to-many relationshipsConsidering data securityBringing in business logicPreparing for growth and change
Linked

Key value pairs in relational databases

Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc

Do I need to create indexes on foreign keys on Oracle?

Foreign Key to non-primary key

Best practices on primary key, auto-increment, and UUID in SQL databases

Difference between primary key and unique key

Clustered vs Non-Clustered