JOIN three tables

Joining three tables in SQL is a common task when you want to combine data stored across multiple related tables. Just like joining two tables, you use the JOIN clause, but you extend it by adding another join condition. The key idea is that each join must connect tables through a common column, usually a primary key and foreign key relationship.

For example, imagine you have three tables: customers, orders, and products. If you want to get customer details along with their orders and the product information, you can write:

SELECT c.customer_name, o.order_id, p.product_name  

FROM customers c  

JOIN orders o ON c.customer_id = o.customer_id  

JOIN products p ON o.product_id = p.product_id;

Here’s how it works:

• The first JOIN connects customers with orders using customer_id.
  
• The second JOIN links orders with products using product_id.
  
• The result includes data from all three tables in a single query.
  

Key points to remember:

• You can use INNER JOIN, LEFT JOIN, or RIGHT JOIN depending on whether you want to include unmatched records.
  
• Always make sure join conditions are correct, otherwise you may get duplicate or missing rows.
  
• Use aliases (like c, o, p) for readability and shorter queries.
  
• Joining three or more tables is possible as long as there’s a logical relationship between them.
  
• By mastering multiple table joins, you can build powerful queries that give complete insights from complex databases. This makes your SQL skills much stronger and more practical.