juniorSQL
What is a LEFT JOIN?
Updated May 17, 2026
Short answer
LEFT JOIN returns all rows from left table and matching right rows.
Deep explanation
If no match exists in the right table, NULLs are returned for right table columns.
Real-world example
Listing all users even if they have no orders.
Common mistakes
- Misinterpreting NULL results as missing data.
Follow-up questions
- When to use LEFT JOIN?
- Can LEFT JOIN be chained?