Inner joins are used for combining data from tables where there is a match in given condition on both tables - usually primary key from one table and foreign key from another are used for matching.
Customers
| customer_id | name | country |
|---|---|---|
| 1 | Alice | USA |
| 2 | Bob | UK |
| 3 | Charlie | Germany |
Orders
| order_id | customer_id | order_amount |
|---|---|---|
| 101 | 1 | 250 |
| 102 | 1 | 125 |
| 103 | 2 | 300 |
| 104 | 4 | 400 |
INNER JOIN QUERY
SELECT Customers.name, Orders.order_amount
FROM Customers
INNER JOIN Orders
ON Customers.customer_id = Orders.customer_id;
Result:
| name | order_amount |
|---|---|
| Alice | 250 |
| Alice | 125 |
| Bob | 300 |
Note: Charlie and order_id 104 are not shown because there's no matching
customer_id
