MySQL PHP填写一个空数组

Question

I have a database in which the size of each service used is being saved. In my table the first column is for name_service , the second for size . So what i need to do is to put the total size of each service, knowing that lines with the same service name may be repeated!

$serviceCounts=array();

while ($row=mysqli_fetch_assoc($result))
{
    $size=$row['size'];
    $service=$row['name_service'];  
}

Answer 1

SQL Solution Check out @Adder solution.

PHP Solution

Before the loop:

$services = array();

Inside the loop:

if(array_key_exists($row['name_service'] , $services))
{
  $services[$row['name_service'] += $row['size'];
}
else
{
  $services[$row['name_service'] = $row['size'];
}

You're basically using a new array named services and checking in the loop if this service already set in the array or not. In case that yes - add to it the new row's size, otherwise add the service name as a new element and set its size.

Answer 2

Use the aggregation mysql functionality:

SELECT sum(size) as size, name_service FROM services GROUP BY name_service;

Untested, you might have to rename the sum(size) as sum_size .

Answer 3

$serviceCounts=array();

while ( $row = mysqli_fetch_assoc($result) )
{
    $size=$row['size'];
    $service=$row['name_service'];  

    if (isset($serviceCounts[ $service ])) {
        $serviceCounts[$service] += $size;
    } else {
        $serviceCounts[$service] = $size;
    }
}

Then you can do this to print out the service name and size:

foreach ($serviceCounts as $name=>$size) {
    echo "$name: $size\n";
}

Answer 4

Do You mean something like that?

$serviceCounts=array();

while ($row=mysqli_fetch_assoc($result) {
    $size=$row['size'];
    $service=$row['name_service'];  

    if (isset($serviceCounts[$service])) {
        $serviceCounts[$service]+=$size;
    } else {
        $serviceCounts[$service]=$size;
    }

}

print_r($serviceCounts);