UNION in SQL Server - Examples & AI Generator

The UNION operator in SQL Server lets you combine results from two or more SELECT statements into a single set—removing duplicates. As SQL Server has its own UNION syntax, even experienced SQL developers and analysts can waste time reviewing syntax or troubleshooting errors. With AI2sql, there’s no coding required—simply describe your intent, and get accurate UNION SQL Server queries in 10 seconds.

UNION Syntax in SQL Server

How to Write UNION Queries

The UNION operator merges the output from multiple SELECT statements, provided they have:

• The same number of columns

• Compatible data types in matching columns

SELECT column1, column2 FROM table1
UNION
SELECT column1, column2 FROM table2;

Note: UNION in SQL Server removes duplicates. Use UNION ALL to include duplicates.

UNION Examples You Can Generate Instantly

1. Combine Customer Emails from Two Tables

SELECT Email FROM Customers
UNION
SELECT Email FROM NewsletterSubscribers;

Get a list of all unique customer and subscriber emails.

2. Merge Product Lists from Separate Brands

SELECT ProductName FROM Electronics
UNION
SELECT ProductName FROM Clothing;

View all products across brands without duplicates.

3. Find All Orders from Different Years

SELECT OrderID, CustomerID FROM Orders2022
UNION
SELECT OrderID, CustomerID FROM Orders2023;

Aggregate orders regardless of order year for unified analysis.

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FAQ: UNION in SQL Server

Can I use ORDER BY with UNION in SQL Server?

Yes, but only on the final SELECT statement result, not within individual queries. Example:

SELECT Name FROM Employees
UNION
SELECT Name FROM Managers
ORDER BY Name;

What is the difference between UNION and UNION ALL?

UNION removes duplicates; UNION ALL does not.

Do columns need to match for UNION in SQL Server?

Yes, all SELECT statements must return the same number of columns with compatible data types.

Looking for a quick reference on SQL Server UNION syntax? Learn UNION with practical guides and AI-backed solutions.

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