How can I do three table JOINs in an UPDATE query?

🔗 Title: Mastering Three Table Joins in UPDATE Queries: A Comprehensive Guide

📝 Introduction: Hey there tech enthusiasts! 👋 Have you ever found yourself scratching your head while trying to perform a three table JOIN in an UPDATE query? 😫 We've got your back! In this guide, we'll break down the common issues, provide easy solutions, and help you master the correct syntax for executing this task effortlessly. So buckle up and let's dive right in! 💪

🔍 Understanding the Question: Our fellow tech-savvy friend recently asked if it's possible to perform three table JOINs in an UPDATE statement, and what the correct syntax for it would be. Great question! Let's tackle it step by step.

💡 The Initial Solution: Before addressing the three table JOIN scenario, let's start with a quick recap. You can perform a two table JOIN in an UPDATE query by using the following syntax:

UPDATE TABLE_A a 
JOIN TABLE_B b ON a.join_col = b.join_col 
SET a.column_c = a.column_c + 1

As you can see, we JOIN two tables and specify the conditions in the ON clause. The SET clause is used to update the desired column(s) in TABLE_A. 👍

💡 The Three Table JOIN Challenge: When it comes to adding a third table to the mix, things get a bit more interesting. Our friend wonders if they should use two JOIN statements (JOIN tableB, tableA JOIN tableB, tableA), but that's not the correct approach. Let's unveil the right way to accomplish this task! 😎

🚀 The Correct Syntax: To perform a three table JOIN in an UPDATE statement, you should use the following syntax:

UPDATE tableC c
JOIN tableB b ON c.join_col = b.join_col
JOIN tableA a ON b.join_col = a.join_col
SET c.column_c = c.column_c + 1

In this example, we JOIN tableC with tableB, and then further JOIN tableA based on the respective join columns. Finally, we update the desired column(s) in tableC using the SET clause. Voila! 🎉

📖 Real-Life Example: Let's grasp the concept better with a practical scenario. Assume we have a system that manages orders, customers, and products. We want to update the order quantity for a specific product given the order ID, customer ID, and product ID. Here's how our UPDATE query would look:

UPDATE orders o
JOIN customers c ON o.customer_id = c.id
JOIN products p ON o.product_id = p.id
SET o.quantity = o.quantity + 1
WHERE o.id = 12345 AND c.id = 555 AND p.id = 789

By using the JOINs, we retrieve the relevant order, customer, and product records, and increment the quantity accordingly. Amazing, right? 😃

💡 Call-to-Action: And there you have it, folks! You've successfully learned how to master three table JOINs in UPDATE queries. Say goodbye to confusion and embrace the power of a well-crafted syntax. 🚀 Feel free to leave a comment if you found this guide helpful or have any other tech-related questions. Stay tuned for more exciting content! Keep coding and keep conquering! 💻💪

Stay curious, stay geeky! 🤓✌️