When working with databases, it is common to use JOIN statements to combine data from multiple tables. In some cases, you may need to specify multiple conditions in the WHERE clause to filter the joined data. This article will guide you on how to use JOINs with multiple conditions in SQL SELECT statements.

The JOIN Statement

The JOIN statement combines rows from two or more tables based on a related column between them. There are different types of JOINs, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and OUTER JOIN. For the purpose of this article, we will focus on the INNER JOIN.

Here’s an example of an INNER JOIN that joins two tables using a common column, “id”:

SELECT * FROM table1
INNER JOIN table2 ON table1.id = table2.id;

Adding Multiple Conditions to the WHERE Clause

To add multiple conditions to the WHERE clause when using joins, you can use logical operators like AND or OR. Let’s consider an example where we want to join two tables, “orders” and “customers”, based on the customer ID and order status:

SELECT *
FROM orders
INNER JOIN customers ON orders.customer_id = customers.id
WHERE customers.country = 'USA'
AND orders.status = 'completed';

In the above example, we are joining the “orders” and “customers” tables using the customer ID. Then, we are filtering the joined data by specifying two conditions in the WHERE clause: customers from the USA and orders with the status “completed”. Both conditions must be true for a row to be included in the result set.

Conclusion

Using JOINs in SQL SELECT statements allows you to combine data from multiple tables. When using multiple conditions in the WHERE clause while joining tables, you can use logical operators like AND or OR to filter the data based on different criteria. Make sure to specify the column names correctly and choose the appropriate JOIN type for your requirements.

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