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SQL joins explained

⬇️1️⃣ Left Join

Returns all records from the left table (A) and the matched records from the right table (B). If there’s no match, it returns NULL on the right side.

💡 Keeps all records from A and fills in matching data from B.

⬇️2️⃣ Left Join Without Overlapping

Returns all records from A that don’t have a match in B.

💡 Ideal for finding exclusive entries in A that aren’t in B.

⬇️3️⃣ Right Join

Opposite of Left Join—returns all records from B and matched records from A. If there’s no match, it returns NULL on the left side.

💡 Focuses on B and brings in data from A where available.

⬇️4️⃣ Right Join Without Overlapping

Returns all records from B that don’t have a match in A.

💡 Perfect for spotting unique entries in B.

⬇️5️⃣ Full Join

Combines results of Left Join and Right Join, returning all records when there is a match in either A or B.

💡 Use this for a complete view of both tables.

⬇️6️⃣ Inner Join

Returns only records that have matching values in both tables.

💡 Best for retrieving intersecting data between A and B.

⬇️7️⃣ Full Join Without Overlapping

Returns all records from A and B where there is no match in the other table.

💡 Use this to see what’s missing in both A and B. Great for identifying data gaps.

🚀 Master SQL Joins for Better Database Queries!

✍️ Credit by: Josep Ferrer

Amr Abdelkarem

I’m Amr Abdelkarem, a PHP Backend Developer with 5+ years of experience building backend-driven systems using PHP, REST APIs, MySQL, and PostgreSQL. I’ve worked on e-commerce workflows, payment integrations, shipping automation, and scalable business logic in production environments. I also have previous experience with WordPress backend development and Django-based systems, and I’m currently focused on Laravel and backend architecture. My certifications include IBM’s Developing Front-End Apps with React, plus certifications in Cloud Computing, HTML/CSS/JavaScript, Software Engineering, Python for Data Science, and Databases and SQL.

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