Oracle SET operation functions: Union, UNION All, Intersect, minus

Union, which is combined with two result sets, excluding duplicate rows, and sorting the default rules;
Union all, which is set up for two result sets, including repeating rows, without sorting;
Intersect, the intersection of two result sets, excluding duplicate rows, and the sorting of the default rules;
Minus, a differential operation on two result sets, excluding duplicate rows, and sorting the default rules.find those records in the first SQL query that are not in the results of the second SQL statement queryHigher performance than not exists
The ORDER BY clause can be specified in the last result set to change the ordering method.

Oracle SET operation functions: Union, UNION All, Intersect, minus