Learn SQL in the Age of AI

Planning Join Paths

Learn how to connect data across tables.

We'll cover the following...

Step 1: Start with a problem, not code
Step 2: Draw the join path
Step 3: Translate the plan into SQL
Step 4: Try an alternative join path
Step 5: Your turn to tweak and plan

Step 1: Start with a problem, not code

So far, you’ve executed joins. Now let’s learn to plan them.

Imagine your database has three tables:

employees contains employee_id, name, department_id.
departments contains department_id, department_name, manager_id.
managers contains manager_id, manager_name.

And your question is: What is each employee’s name, their department name, and their manager’s name?

Before writing SQL, pause.

Can you visualize the path of relationships? Try to map it mentally or sketch it: employees → departments → managers

Prompt hint: Describe how to plan the join path between employees, departments, and managers to answer the ...