Suppose there are two tables A and B, each with only one field PHONE
1、MINUS
SELECT PHONE FROM A MINUS SELECT PHONE FROM B; Equivalent to the result set obtained by subtracting the result B from the result set A. The same effect can also be achieved with SELECT PHONE FROM A WHERE NOT EXISTS(SELECT 1 FROM B WHERE A.PHOEN=B.PHONE).
2、INTERSECT
SELECT PHONE FROM A INTERSECT SELECT PHONE FROM B; is equivalent to finding the intersection of result set A and result set B.
3、UNION
SELECT PHONE FROM A UNION SELECT PHONE FROM B; is equivalent to finding the combination of result set A and result set B, and deduplication.
4. UNION ALL
SELECT PHONE FROM A UNION ALL SELECT PHONE FROM B; is equivalent to seeking the combination of result set A and result set B, without deduplication.
Reprinted: https://my.oschina.net/u/2003855/blog/307369