Sum values in multidimensional array (selecting multiple columns with multiple rows)

Question

Let's say I have 5 different columns, a, b, c, d, e, and I'm selecting multiple rows:

$result = mysqli_query($conn,"SELECT a,b,c,d,e FROM posts WHERE submitter='$user'");

while ($row = mysqli_fetch_assoc($result)){
  $ratings[] = $row; 
}

Example:

The user has 3 posts, so it'll select 3 rows in the query.

I want to sum all of the rows' values for a (and the rest of course).

e.g.

row 1 a value = 4

row 2 a value = 10

row 3 a value = 1

So I need to sum all of those to get 15.

I know to use array_sum($ratings) to find the sum of the array but only if you select one column (a) which can have multiple rows, but this is multi-dimensional right due to multiple column values being selected?

possible duplicate of MySQL Sum() multiple columns

Blue
– Blue

2015-06-14 06:45:48 +00:00
Commented Jun 14, 2015 at 6:45 — Blue
– Blue, Commented Jun 14, 2015 at 6:45

souslov · Accepted Answer · 2015-06-14 06:46:10Z

0

You can just use sum in your query:

select sum(a)
     , sum(b)
     , sum(c)
     , sum(d)
     , sum(e)
from posts
where submitter = '$user'

answered Jun 14, 2015 at 6:46

souslov

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8 Comments

frosty Over a year ago

What will be stored in the $ratings array?

frosty Over a year ago

I think you read that wrong.. -What- will be stored in there I mean?

souslov Over a year ago

@frosty: sorry, there will be an array of sums for each column, you can var_dump result to see it yourself.

frosty Over a year ago

Thanks, I think it's still producing a multi-dimensional array tho. array(1) { [0]=> array(5) { ["sum(a)"]=> string(2) "22" --- how do I retrieve the "22"?

frosty Over a year ago

Yes, just saw your edit. Was trying $row[0] and $row['a'] but wasn't working, $row['sum(a)'] works though

|

enrico.bacis · Accepted Answer · 2015-06-14 08:18:15Z

0

You can use count aggregate function and group by in MySQL.

SELECT
  submitter,
  count(a) as rating
FROM posts
WHERE submitter='$user'
GROUP BY submitter

A a result you will get something like that:

some submitter, 3
another submitter, 10
one more submitter, 1

Is this helpful?

edited Jun 14, 2015 at 8:18

enrico.bacis

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answered Jun 14, 2015 at 6:46

Aleksei Akireikin

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1 Comment

frosty Over a year ago

ty for the answer, I was able to get it working with the other answer tho

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