SQL to add a summary row to MySQL result set

Question

If I have a MySQL table such as:

I want to use SQL to calculate the sum of the PositiveResult column and also the NegativeResult colu

Answer 1

I would also do this in the presentation layer, but you can do it MySQL...

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table
(id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,pos DECIMAL(5,2)
,neg DECIMAL(5,2)
);

INSERT INTO my_table VALUES
(1,0,0),
(2,1,-2.5),
(3,1.6,-1),
(4,1,-2);


SELECT COALESCE(id,'total') my_id,SUM(pos),SUM(neg) FROM my_table GROUP BY id WITH ROLLUP;

+-------+----------+----------+
| my_id | SUM(pos) | SUM(neg) |
+-------+----------+----------+
|     1 |     0.00 |     0.00 |
|     2 |     1.00 |    -2.50 |
|     3 |     1.60 |    -1.00 |
|     4 |     1.00 |    -2.00 |
|  total|     3.60 |    -5.50 |
+-------+----------+----------+
5 rows in set (0.02 sec)

Here's a hack for the amended problem - it ain't pretty but I think it works...

SELECT COALESCE(id,'') my_id
     , SUM(pos)
     , SUM(neg)
     , COALESCE(string,'') n
  FROM my_table 
 GROUP 
    BY id
     , string
  WITH ROLLUP
HAVING n <> '' OR my_id = ''
;