What is the difference between SQL Joins and Unions?

What is the difference between SQL Joins and Unions?

SQL Joins combine rows from two or more tables based on a related column, while Unions combine the result sets of two or more SELECT statements.

Can you give me an example of a SQL Join?

Sure! A simple example is an INNER JOIN, which returns records that have matching values in both tables. For instance, if you have a 'Customers' table and an 'Orders' table, you can join them on 'CustomerID' to get a list of customers with their orders.

And what about a Union? How does that work?

A Union combines the results of two or more SELECT queries into a single result set. For example, if you have two tables with similar structures, you can use a UNION to get all unique records from both tables.

Are there any performance differences between using Joins and Unions?

Yes, Joins are generally more efficient for combining related data, while Unions can be slower since they require combining and deduplicating results from separate queries.