Making CASE Statements dynamic with Jinja Loops in dbt

📘Introduction

In this hands-on dbt tutorial, you’ll learn how to make your SQL transformations dynamic and reusable by using Jinja loops inside CASE statements. This approach helps you replace repetitive SQL logic with concise, maintainable code — a valuable skill for any Data Engineer.

✅ Prerequisites

☑️ A dbt project set up
☑️ Source data loaded into your data warehouse
☑️ Source configurations defined in sources.yml

🧠 Practical Example

Let’s walk through an example. In our dbt project, the table dim_student contains the following data:

We want to create a new dbt model that maps each major_id to its corresponding major_name. The mapping is defined as follows:

Typically, you would handle this with a CASE statement. However, instead of manually writing each WHEN clause, we can use a Jinja loop to generate them dynamically.

🗂️1️⃣ Create new .sql file inside the models/ folder

Inside your dbt project, navigate to the models/ folder and create a new SQL file named student.

⚙️3️⃣ Use loop with CASE statement within your SQL code

Now, let's implement the mapping by combining a CASE statement with a Jinja loop.