SQL LEARNING SERIES PART-15

Complete SQL Topics for Data Analysis
-> https://t.me/sqlspecialist/523

Today, we will learn about Advanced Join Techniques:

Beyond basic joins, there are scenarios where advanced join techniques become useful.

#### Self-Join:
A self-join occurs when a table is joined with itself. It's useful when you want to compare rows within the same table.

SELECT e1.employee_id, e1.first_name, e1.manager_id, e2.first_name AS manager_name
FROM employees e1
JOIN employees e2 ON e1.manager_id = e2.employee_id;

This query retrieves employee details and the corresponding manager's name from the same "employees" table.

#### Cross Join:
A cross join returns the Cartesian product of two tables, meaning all possible combinations of rows.

SELECT * FROM table1
CROSS JOIN table2;

#### Example:

SELECT product_name, category_name
FROM products
CROSS JOIN categories;

This query returns all possible combinations of product names and category names.

Understanding these advanced join techniques expands your ability to work with diverse data relationships.

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Hope it helps :)