Implicit Join

Also known as traditional or comma-separated joins, implicit joins specify the join condition using the WHERE clause. Tables are listed in the FROM clause, separated by commas, and the join condition is specified in the WHERE clause using equality operators. Implicit joins are considered outdated and less readable compared to explicit joins.

Consider the following database,

Example 1

SELECT orders.order_id, orders.order_date, customers.customer_name
FROM orders, customers
WHERE orders.customer_id = customers.customer_id;

Output:

Explanation: This output lists the order ID, order date, and customer name for each order in the database. The query combines data from the orders table and the customers table using an implicit join, where the customer_id from the orders table matches the customer_id from the customers table. It displays the order information alongside the corresponding customer names.

Example 2

SELECT orders.order_id, orders.total_amount, customers.city
FROM orders, customers
WHERE orders.customer_id = customers.customer_id
AND customers.city = 'New York';

Output:

Explanation: This output presents the order ID, total amount, and city for each order placed by customers residing in New York. The query combines data from the orders table and the customers table using an implicit join, similar to the first example. Additionally, it includes an additional condition in the WHERE clause to filter the results, showing only orders from customers located in New York.

SQL Server is a widely used relational database management system (RDBMS) that provides a robust and scalable platform for managing and organizing data. MySQL is an open-source software developed by Oracle Corporation, that provides features for creating, modifying, and querying databases. It utilizes Structured Query Language (SQL) to interact with databases, making it a popular choice for web applications and various software systems. MySQL’s versatility, reliability, and ease of use make it a preferred solution for developers and organizations seeking efficient data management capabilities.

In this article, you will learn about, Explicit vs implicit SQL Server joins.