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'd recommend doing this at the presentation layer. To do something like this in SQL is also possible.

create table test (
  keywordid int, 
  positiveresult decimal(10,2), 
  negativeresult decimal(10,2)
);
insert into test values 
(1, 0, 0), (2, 1, -2.5), (3, 1.6, -1), (4, 1, -2);

select * from (
    select keywordid, positiveresult, negativeresult
    from test
      union all
    select null, sum(positiveresult), sum(negativeresult) from test
) main
order by
case when keywordid is null then 1000000 else keywordid end;

I added ordering using a arbitrarily high number if keywordid is null to make sure the ordered recordset can be pulled easily by the view for displaying.

Result:
+-----------+----------------+----------------+
| keywordid | positiveresult | negativeresult |
+-----------+----------------+----------------+
|         1 |           0.00 |           0.00 |
|         2 |           1.00 |          -2.50 |
|         3 |           1.60 |          -1.00 |
|         4 |           1.00 |          -2.00 |
|      NULL |           3.60 |          -5.50 |
+-----------+----------------+----------------+