SQL Join Visualizer
NewVisualize INNER, LEFT, RIGHT, FULL, and CROSS joins with a Venn diagram and real computed results from editable sample tables.
Table A: users
Table B: orders (user_id,item)
Edit the CSV tables above (Table A's id joins to Table B's user_id) — the result table is computed live using real join logic against your data, not a static example, so you can see exactly which rows come from unmatched sides in LEFT/RIGHT/FULL joins.
Frequently Asked Questions
Are the result rows actually computed, or just illustrative examples?
They're actually computed — the tool parses your two editable CSV tables and runs real join logic (matching Table A's key against Table B's key) to produce the result set live, so if you edit a row, the output updates to reflect exactly what a real SQL JOIN would return for that data.
What's the difference between LEFT JOIN and RIGHT JOIN?
LEFT JOIN keeps every row from Table A, filling in NULLs for any row that has no match in Table B. RIGHT JOIN does the mirror opposite — every row from Table B is kept, with NULLs filled in for unmatched rows in Table A. They return the same data, just with the tables' roles swapped.
What does FULL OUTER JOIN do?
It combines LEFT and RIGHT JOIN — every row from both tables appears in the result, with NULLs filled in on whichever side didn't have a match. Note that not all databases support FULL OUTER JOIN directly (MySQL notably doesn't, though it can be simulated with a UNION of LEFT and RIGHT JOIN).
What is CROSS JOIN and when would I use it?
CROSS JOIN produces the Cartesian product — every row of Table A paired with every row of Table B, regardless of any matching key. It's used far less often than the other join types, mainly for generating combinations (like pairing every size with every color in a product catalog).
Why does the Venn diagram change shading between join types?
It's a visual aid showing which "region" of the two tables the join keeps: INNER JOIN emphasizes only the overlap, LEFT JOIN emphasizes all of A plus the overlap, RIGHT JOIN emphasizes all of B plus the overlap, and FULL/CROSS emphasize both circles fully.