Inner, Left, Right, and Outer
Choosing the join that keeps the right rows.
Two Tables, One Question
Real data rarely lives in one table. A join combines two tables into one by matching rows on a shared column.
The Key Column
Every join needs a key: the column whose values link rows across both tables, like a shared customer id.
All lessons in this course
- Inner, Left, Right, and Outer
- Merge on Keys and Indexes
- concat to Stack and Append
- Diagnose Bad Joins