What does INNER JOIN return?

INNER JOIN returns only the rows where there is a matching value in both tables based on the join condition. Rows that have no match in the other table are excluded from the result.

Is INNER JOIN the same as JOIN?

Yes. In SQL, JOIN and INNER JOIN are equivalent. The word INNER is optional; when you write JOIN without specifying the type, SQL performs an INNER JOIN by default.

When should I use INNER JOIN instead of LEFT JOIN?

Use INNER JOIN when you only want rows that have matches in both tables. Use LEFT JOIN when you want to keep all rows from the left table, even if there is no match in the right table.

SQL Inner Join

SQL > SQL JOIN > Inner Join

An inner join in SQL returns rows where there is at least one match on both tables. Let's assume that we have the following two tables,

Key Takeaway: INNER JOIN is the most common join type. It returns only rows where the join condition is met in both tables — rows without a match in either table are excluded from results.

Table Store_Information

Store_Name	Sales	Txn_Date
Los Angeles	1500	Jan-05-1999
San Diego	250	Jan-07-1999
Los Angeles	300	Jan-08-1999
Boston	700	Jan-08-1999

Table Geography

Region_Name	Store_Name
East	Boston
East	New York
West	Los Angeles
West	San Diego

We want to find out sales by store, and we only want to see stores with sales listed in the result set. To do this, we can use the following SQL statement using INNER JOIN:

SELECT A1.Store_Name STORE, SUM(A2.Sales) SALES
FROM Geography A1
INNER JOIN Store_Information A2
ON A1.Store_Name = A2.Store_Name
GROUP BY A1.Store_Name;

Result:

STORE	SALES
Los Angeles	1800
San Diego	250
Boston	700

By using INNER JOIN, the result shows 3 stores, even though we are selecting from the Geography table, which has 4 rows. The row "New York" is not selected because it is not present in the Store_Information table.

Frequently Asked Questions

Why does INNER JOIN exclude "New York" in the example above?

"New York" appears in the Geography table but not in Store_Information. Because INNER JOIN requires a match in both tables, rows with no matching entry are excluded from the result set.

Can INNER JOIN be used with more than two tables?

Yes. You can chain multiple INNER JOINs: FROM t1 INNER JOIN t2 ON ... INNER JOIN t3 ON .... Each JOIN adds another table, requiring a matching condition.

What is the difference between INNER JOIN and CROSS JOIN?

INNER JOIN returns only matching rows (filtered by the ON condition). CROSS JOIN returns the Cartesian product of both tables — every row from the first table paired with every row from the second — no condition needed.

Does INNER JOIN affect performance?

Yes. JOINs can be expensive on large tables. Ensure that the columns used in the ON condition are indexed for best performance.

Next: SQL Outer Join

This page was last updated on March 19, 2026.

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