Question

I have this MySQL query:

SELECT DAYOFYEAR(`date`)  AS d, COUNT(*) 
FROM  `orders` 
WHERE  `hasPaid` > 0
GROUP  BY d
ORDER  BY d

Which returns something like this:

d  | COUNT(*) |
20 |  5       |
21 |  7       |
22 | 12       |
23 |  4       |

What I’d really like is another column on the end to show the running total:

d  | COUNT(*) | ??? |
20 |  5       |   5 |
21 |  7       |  12 |
22 | 12       |  24 |
23 |  4       |  28 |

Is this possible?

Answer 1

MySQL Warning: Setting user variables within expressions is deprecated and will be removed in a future release.

Perhaps a simpler solution for you and prevents the database having to do a ton of queries. This executes just one query then does a little math on the results in a single pass.

SET @runtot:=0;
SELECT
   q1.d,
   q1.c,
   (@runtot := @runtot + q1.c) AS rt
FROM
   (SELECT
       DAYOFYEAR(`date`) AS d,
       COUNT(*) AS c
    FROM  `orders`
    WHERE  `hasPaid` > 0
    GROUP  BY d
    ORDER  BY d) AS q1

This will give you an additional RT (running total) column. Don’t miss the SET statement at the top to initialize the running total variable first or you will just get a column of NULL values.