mysql - SUM(DISTINCT) Based on Other Columns

Question

I currently have a table that looks something like this:

+------+-------+------------+------------+
| id   | rate  | first_name | last_name  |
+------+-------+------------+------------+

What I need to do is get the SUM of the rate column, but only once for each name. For example, I have three rows of name John Doe, each with rate 8. I need the SUM of those rows to be 8, not 24, so it counts the rate once for each group of names.

SUM(DISTINCT last_name, first_name) would not work, of course, because I'm trying to sum the rate column, not the names. I know when counting individual records, I can use COUNT(DISTINCT last_name, first_name), and that is the type of behavior I am trying to get from SUM.

How can I get just SUM one rate for each name?

Thanks in advance!

Answer 1

select sum (rate)
from yourTable
group by first_name, last_name

Edit

If you want to get all sum of those little "sums", you will get a sum of all table..

Select sum(rate) from YourTable

but, if for some reason are differents (if you use a where, for example) and you need a sum for that select above, just do.

select sum(SumGrouped) from 
(    select sum (rate) as 'SumGrouped'
    from yourTable
    group by first_name, last_name) T1