<P> Set operations allow the results of multiple queries to be combined into a single result set . Set operators include UNION, INTERSECT, and EXCEPT . </P> <P> In SQL the UNION clause combines the results of two SQL queries into a single table of all matching rows . The two queries must result in the same number of columns and compatible data types in order to unite . Any duplicate records are automatically removed unless UNION ALL is used . </P>

What is the difference between union and intersection in sql