Meaning of JOIN (SQL)

Simple definition

A SQL operation that combines rows from two or more database tables based on a related column between them.

How to use JOIN (SQL) in a professional context

Commonly used in database management to retrieve data spread across multiple tables.

Concrete example of JOIN (SQL)

A query combining a “Customers” table and an “Orders” table: SELECT Customers.Name, Orders.OrderID FROM Customers JOIN Orders ON Customers.CustomerID = Orders.CustomerID;

What are the types of JOINS in SQL?

Common types include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.

What is the difference between INNER JOIN and OUTER JOIN?

INNER JOIN returns only matching records, while OUTER JOIN includes non-matching rows with NULL values.

Do JOINS work only on primary keys?

No, they can work on any related columns, but primary keys are often used.
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