# Return the Set Union of Two Sequences

**.NET Framework (current version)**

Use the Union<TSource> operator to return the set union of two sequences.

## Example

This example uses Union<TSource> to return a sequence of all countries in which there are either Customers or Employees.

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In LINQ to SQL, the Union<TSource> operator is defined for multisets as the unordered concatenation of the multisets (effectively the result of the

UNION ALLclause in SQL).