LEFT JOIN vs. LEFT OUTER JOIN in SQL Server

If you’ve written SQL queries before, you’ve probably come across both LEFT JOIN and LEFT OUTER JOIN. At first glance, they might seem different — especially if you’re new to SQL — but here’s the truth: they’re exactly the same in SQL Server!

Yep, that’s right — there’s no difference in functionality between LEFT JOIN and LEFT OUTER JOIN.

 So why are there two terms?

• LEFT OUTER JOIN is the complete, more descriptive form.
  
• LEFT JOIN is simply a shortened version — and it’s the one most developers use in practice.
  

 What does a LEFT JOIN actually do?

A LEFT JOIN returns all records from the left table, and the matched records from the right table. If there’s no match, you’ll still get the left-side data, but with NULL in the right-side columns.

 Example:

SELECT a.name, b.order_id

FROM customers a

LEFT JOIN orders b ON a.id = b.customer_id;

This will return all customers, including those who haven’t placed any orders.

 TL;DR:

LEFT JOIN = LEFT OUTER JOIN

• Use whichever you prefer — just stay consistent!
  
• Both are great when you need to include unmatched data from the left table.