EXAMPLE 1 — Problem: How can we find duplicate last names, in the combined list of last names from both the students and students tables?​ ​Approach: We must get the count of each last name. Then we will know that any last name with a count > 1 is a duplicate. Begin by…

Set Operations & Joins, Union, Intersect, INNER JOIN, LEFT, RIGHT, FULL JOIN — Set Operations Allow us to query from more than one table at a time Sample Data: UNION

Aggregations, GROUP BY, HAVING — Aggregate functions Aggregations