如何在mysql中找到行总和？

Question

I am trying to get all rows from table. I could do that job properly. But the problem comes when I put each row values as percentage and tried to sum the percentage. For example, I am using the following query to output all the rows:

SELECT SUM( Mark_score ) / SUM( Full_mark ) *50 AS Score
FROM nuexam
WHERE regd = '22'
GROUP BY subject

With the above query I got the following output:

I want to sum total of this Score . This is so far what I could output. Any help is very much appreciated. I will also welcome the php solution.

Answer 1

Simply running a nested query should work:

SELECT SUM(s) as Score
FROM (SELECT SUM( Mark_score ) / SUM( Full_mark ) *50 AS s
    FROM nuexam
    WHERE regd = '22'
    GROUP BY subject) table

Answer 2

If you want to get the individual scores along with the total, then use with rollup . The proper way for your data would be:

select coalesce(subject, 'Total'), sum(t.Score)
from (SELECT subject, SUM( Mark_score ) / SUM( Full_mark ) *50 AS Score
      FROM nuexam
      WHERE regd = '22'
      GROUP BY subject
     ) t
group by subject with rollup;

Answer 3

http://sqlfiddle.com/#!2/a505a/4

select sum(t.Score) from 
(SELECT SUM( Mark_score ) / SUM( Full_mark ) *50 AS Score
FROM nuexam
WHERE regd = '22'
GROUP BY subject ) t