This operator combines the result set of multiple queries or you can say it appends the result set of next query to the previous query result set.
Some points need to consider:-
- Number of columns in all result set or in all queries must be same.
- Order of columns must be same in all queries.
- Data type of columns must be same.
- It returns the unsorted result set.
- It returns all records whether its duplicate record or not.
