UNION in MySQL - Examples & AI Generator

Mastering the UNION operation in MySQL lets you combine results from multiple SELECT statements, but getting the syntax right (column order, matching data types, duplicates) can be tricky. Whether you're a developer switching databases or a data analyst wanting efficiency, writing UNION queries by hand slows you down. AI2sql instantly generates production-ready UNION statements from natural language—so you can skip memorization and avoid errors, with no coding required.

UNION Syntax in MySQL

Basic Syntax

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

• SELECT statements must have same number of columns and compatible data types.

• UNION removes duplicate rows by default. Use UNION ALL to include duplicates.

• ORDER BY applies to the final, combined result set.

UNION Examples You Can Generate Instantly

Copy, paste, and adjust these UNION MySQL examples for your use case—or let AI2sql generate what you need in 10 seconds.

1. Merging Customer Emails from Multiple Regions

SELECT email FROM customers_usa
UNION
SELECT email FROM customers_europe;

2. Combining Orders and Returns for Yearly Stats

SELECT order_id, customer_id, order_date AS activity_date, 'Order' AS activity_type FROM orders
UNION
SELECT return_id, customer_id, return_date AS activity_date, 'Return' AS activity_type FROM returns;

3. Unified Product Listings from Two Tables

SELECT product_name, price FROM products_online
UNION ALL
SELECT product_name, price FROM products_instore;

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Why Use AI2sql Instead of Manual UNION Coding

• Instant generation: Go from business question to query in seconds.

• No syntax guesswork: AI2sql knows every MySQL UNION rule—no more column mismatches or manual typing.

• Built for professionals: Trusted by 50,000+ users across 80+ countries for accurate, production-grade SQL.

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Frequently Asked Questions

What is the difference between UNION and UNION ALL in MySQL?

UNION removes duplicates from combined results, while UNION ALL includes all rows (including duplicates).

Why must SELECTs in a UNION have the same number of columns?

MySQL requires each SELECT in a UNION to output exactly the same number of columns, and corresponding columns must have compatible data types.

Can I use ORDER BY or LIMIT with UNION?

Yes, but these clauses apply to the final result, not individual SELECT statements.

Conclusion

Writing UNION queries in MySQL is powerful, but the syntax can be easy to forget—especially with more complex business needs. AI2sql makes generating UNION statements instant, error-free, and accessible to everyone. Generate Your First Query Now and never hand-code UNION in MySQL again.