What is the difference between INNER JOIN and LEFT JOIN?

INNER JOIN returns only rows that have matching values in both tables. LEFT JOIN returns all rows from the left table plus matching rows from the right table — rows with no match in the right table get NULL values.

What does a FULL OUTER JOIN return?

FULL OUTER JOIN returns all rows from both tables. Where there is no match on either side, NULLs fill the missing columns. It is the union of LEFT JOIN and RIGHT JOIN.

When should I use a CROSS JOIN?

CROSS JOIN returns every combination of rows from two tables (cartesian product). Use it when you need to generate all possible pairings — for example, combining every size with every colour in a product catalog.

A SELF JOIN joins a table to itself using table aliases. It is useful for hierarchical data such as employee–manager relationships, or comparing rows within the same table.

Is RIGHT JOIN just a reversed LEFT JOIN?

Yes. RIGHT JOIN returns all rows from the right table plus matching rows from the left. It is functionally identical to swapping the tables in a LEFT JOIN, so most developers prefer LEFT JOIN for consistency.

Does this tool run queries on a real database?

No — all logic runs entirely in your browser. No data is sent to any server. The sample tables and results are computed in TypeScript from pre-defined datasets, so the tool works offline too.

Free SQL Reference Tool

Visualize Every
SQL JOIN Type

Interactive Venn diagrams, sample tables, and ready-to-copy SQL code for INNER, LEFT, RIGHT, FULL OUTER, CROSS, and SELF JOINs — understand the difference in seconds.

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Visual Venn Diagrams

See exactly which rows each JOIN type returns, rendered as clear, color-coded Venn diagrams.

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Live Sample Data

Explore real input tables and computed result sets for every JOIN type side by side.

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Copy-Ready SQL

Get a correct, formatted SQL snippet for each JOIN type — paste straight into your query editor.

INNER JOIN

Returns only the rows that have matching values in BOTH tables.

SQL

SELECT a.id, a.name, b.dept
FROM employees a
INNER JOIN departments b ON a.id = b.id;

Input Tables

Table A — employees

id	name
1	Alice
2	Bob
3	Carol
4	Dave

Table B — departments

id	dept
2	Engineering
3	Design
5	Marketing

Result

2 rows

a.id	a.name	b.id	b.dept
2	Bob	2	Engineering
3	Carol	3	Design

Quick Comparison

Frequently Asked Questions

Everything you need to know about SQL JOIN Visualizer.

Visualize EverySQL JOIN Type

Visual Venn Diagrams

Live Sample Data

Copy-Ready SQL

Frequently Asked Questions

Visualize Every
SQL JOIN Type