What is the difference between Union and Join?
UNION combines the results of two or more queries into a single result se. JOINs you can retrieve the data from two or more tables based on logical relationship between the tables.
if tables are joined one above other it is union if tables are joined side by side it is join
'union' selects the same type of data (the same columns) from more than one table - like adding the next table to the bottom of the previous one; 'join' selects different type of data (different columns) from more than one table - like adding more columns next to the first table.
What many SoloLearn users are doing is searching "join vs union" on the Internet and posting that as part of their answer. I am going to respect authors or bloggers response and I am going to provide you two links that is going to take you to the concepts and examples, step-by-step in what is a "join" and what is an "union". At the end you will have your own understanding and conclusion what is a join vs union. http://www.w3schools.com/sql/sql_join.asp http://www.w3schools.com/sql/sql_union.asp