**UNION** — combine results from two queries. Types: - **UNION** — removes duplicates. - **UNION ALL** — keeps duplicates. **Example:** ```sql -- All customers from US and Canada SELECT name, country FROM customers WHERE country = 'USA' UNION SELECT name, country FROM customers WHERE country = 'Canada'; -- With duplicates SELECT customer_id FROM orders_2023 UNION ALL SELECT customer_id FROM orders_2024; ``` **Requirements:** - Same number of columns. - Compatible data types. **BA use:** - Combine data sources. - Create comprehensive reports.

Business Analyst: What is a SQL UNION?

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📊Business Analyst⚡ middle

What is a SQL UNION?

UNION — combine results from two queries.

Types:

UNION — removes duplicates.
UNION ALL — keeps duplicates.

Example:

sql

1-- All customers from US and Canada
2SELECT name, country FROM customers WHERE country = 'USA'
3UNION
4SELECT name, country FROM customers WHERE country = 'Canada';
5
6-- With duplicates
7SELECT customer_id FROM orders_2023
8UNION ALL
9SELECT customer_id FROM orders_2024;

Requirements:

Same number of columns.
Compatible data types.

BA use:

Combine data sources.
Create comprehensive reports.

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