What is the purpose of the UNION keyword in SQL?

The keyword UNION is used to combine the results of two or more SELECT statements into a single result set. In this case:

• Each SELECT statement must return the same number of columns.
• Corresponding columns in each SELECT statement should have similar data types.

By default, UNION removes all duplicate rows from the combined set. If you want to include all rows, including duplicates, use UNION ALL.

Example of using UNION:

SELECT column1, column2 FROM Table1
UNION
SELECT column1, column2 FROM Table2;