SQL Joins

A JOIN clause is used to combine rows from two or more tables based on a related column between them.

Example Tables

Orders Table:

Customers Table:

The relationship between the tables is via the CustomerID column.

INNER JOIN Example

This query selects records that have matching values in both tables:

SELECT Orders.OrderID, Customers.CustomerName, Orders.OrderDate
FROM Orders
INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;

SQL Joins

JOIN Types Summary

• INNER JOIN: Matching records in both tables
• LEFT JOIN: All from left + matched from right
• RIGHT JOIN: All from right + matched from left
• FULL OUTER JOIN: All records from both tables