Question

How can I select a COUNT based on ANOTHER ROW in the SAME TABLE so it doesn’t count duplicate values?

I want to select the COUNT(id) as TOTAL, only ONCE per email.

This is my starting point:

SELECT COUNT(id) AS total 
FROM entries 
WHERE tracking_code = 'test2'

What I’m trying to accomplish is something like this:

SELECT COUNT(id) AS total 
FROM entries 
WHERE id IN (SELECT DISTINCT email FROM entries)

Answer 1

Try this:

select count(distinct email) from entries