Fundamentals of Data Analysis Relational model diagrams

35. Relational model diagrams

To understand the data model of a company or a product feature it usually helps to draw a diagram. The type of relationship between tables is reflected in the line that connects tables.

one-to-one

A simple line represents a one-to-one relationship. A dot highlights the table that has a foreign key. Here’s how we would represent the relationship between users and profile (user has one profile):

One to one

one-to-many

To highlight a one-to-many relationship we need to connect tables with a line that resembles a fork. Records from a table with a single line (...

“well worth the money”
Sign up and check out 36 free lessons and exercises.

Anatoli Makarevich, author of SQL Habit About SQL Habit

Hi, it’s Anatoli, the author of SQL Habit. 👋

SQL Habit is a course (or, as some of the students say, “business simulator”). It’s based on a story of a fictional startup called Bindle. You’ll play a role of their Data Analyst 📊 and solve real-life challenges from Business, Marketing, and Product Management.

SQL Habit course is made of bite-sized lessons (you’re looking at one atm) and exercises. They always have a real-life setting and detailed explanations. You can immediately apply everything you’ve learned at work. 🚀

“well worth the money”

Fluent in SQL in a month

Master Data Analysis with SQL with real life examples from Product Management, Marketing, Finance and more.
-- Type your query here, for example this one -- lists all records from users table: SELECT * FROM users
Loading chart... ⏳
Previous lesson: Relation types: one to one, one to many, many to many
Next lesson: Comparing dates and datetimes