I’m trying to understand which approach works better for joining multiple tables in MySQL. Both queries seem to produce the same results, but I want to know if there are performance differences or other considerations.
First approach using comma syntax:
SELECT
*
FROM
orders, customers, products
WHERE
orders.customer_id = customers.customer_id AND
orders.product_id = products.product_id AND
orders.order_date > '2020-01-01';
Second approach with explicit joins:
SELECT
*
FROM
orders
INNER JOIN customers ON
orders.customer_id = customers.customer_id
INNER JOIN products ON
orders.product_id = products.product_id
WHERE
orders.order_date > '2020-01-01';
Which one should I use? Are there situations where one performs better than the other? I’m working with medium-sized tables and want to make sure I’m following best practices.
i’d say go for explicit joins. they r clearer and help avoid mistakes like cartesian products. mysql optimizes both, so it’s not about speed but about keeping your queries easy to read and maintain. makes life easier down the line, trust me!
From my experience working with MySQL databases over the past few years, both syntaxes generate identical execution plans when properly written. The MySQL optimizer treats them the same way internally, so performance is essentially equivalent. However, I strongly recommend the explicit JOIN syntax for practical reasons. When debugging complex queries or when someone else needs to modify your code later, the explicit syntax makes the relationships between tables much clearer. I’ve seen too many cases where comma-separated joins led to accidental cross joins when developers forgot a WHERE condition, which can be catastrophic with larger datasets. The explicit syntax also makes it easier to switch between different join types if requirements change. While your example works fine either way, maintaining consistency with explicit joins will save you headaches as your queries become more complex.