how Union keyword decide to remove duplicate value if there are multi column result set.

Question

For eg: If I have two table with name and email_id column in both. And I want to make a union set from both the table , then my query will be
SELECT name, email_id FROM table1
UNION
SELECT name,email_id FROM table2
Then how this query work to remove duplicate records and from which column it will prefer to remove duplicate.. just curious to know this things..

Answer 1

If you have a record from each table with the same name and email, only one copy will be included in the union results.