INNER JOIN Practice

INNER JOIN returns only rows that have matches in BOTH tables. If there's no match, the row is excluded.

INNER JOIN Visualization

Table A          Table B
+----+           +----+
| 1  |    JOIN   | 1  |  ← Matched (included)
| 2  |    ====   | 3  |
| 3  |           | 4  |  ← No match in A (excluded)
+----+           +----+
                   ↑ No match in B (2 excluded)

Result: Only rows 1 and 3

Exercises

Using Table Aliases

Table aliases make queries more readable:

Free Practice

Try:

• Find the total spent by each user
• List products that have been ordered (join with order_items)
• Count products per category