Mysql get sum of column_1 based on distinct value in column_2

Question

I have this table:

+-----+--------+ 
|col1 |   col2 |
+-----+--------+
|   1 |     12 | 
|   1 |     12 |
|   2 |     13 |
|   4 |     15 | 
|   2 |     13 |
|   3 |     14 |
|   3 |     14 |
|   1 |     12 |
+-----+--------+

I'm looking for Total sum of col2 for distinct col1.

Answer 1

select col1, sum(col2) from mytable group by col1

Answer 2

With:

SELECT DISTINCT col1, col2 FROM tablename

get the distinct rows of the table and then get the sum:

SELECT SUM(col2) AS total
FROM (SELECT DISTINCT col1, col2 FROM tablename) t

Answer 3

then you just have to add another query select sum(col2) from myTable