Mysql – How to query a column for duplicates values but have different values in a different column?

I have a table with the following structure:

Id  Email   Unsubscribed
1   email_1 0
2   email_2 0
3   email_3 1
4   email_1 1
5   email_4 1
6   email_3 0
7   email_1 0
8   email_4 1

I am trying to query for all duplicate emails that have different values in the Unsubscribed column. I want to return something like this based on the above example:

Email
email_1
email_3

Answer

It think you just want this:

SELECT Email
FROM yourTable
GROUP BY Email
HAVING MIN(Unsubscribed) <> MAX(Unsubscribed);

The HAVING clause would only assert to true if a given email appeared with more than one value for unsubscribed.