基于键的数组总和（按用户分组）

Question

enter image description here

这是我从mysql获得的第一个数组

Array    
([0] => Array
    (
        [created_by] => 4
        [count] => 1
        [total] => 300
    )

[1] => Array 
    (
        [created_by] => 4
        [count] => 1
        [total] => 450
    )

[2] => Array
    (
        [created_by] => 3
        [count] => 1
        [total] => 500
    )

）

我需要输出

[0] => Array
    (
        [created_by] => 4
        [count] => 2
        [total] => 750
    )

[1] => Array
    (
        [created_by] => 3
        [count] => 1
        [total] => 500
    )

基于created_by的数组总和 需要按created_by count分组。