你好，每一个我有小问题是有在mysqli和php
我有一个具有多行的表，并且我将在基于行的这些值的和的阵列中拾取一列值。

这里我将像这样放置图像array [0]+ array [0]+ array [0]=某个值
并且数组[n]+数组[n]+数组[n]=某个值可以打印出来
我的密码是

<?php  
$sql2="SELECT * FROM `purchase_data` where `project_id` ='$proid'";
$result2 = $conn->query($sql2);
$count2=$result2->num_rows;

if ($count2 > 0) {
    $x=1;
    $tot = 0;
    while ($pur_row = $result2->fetch_assoc()) {
        //$proid =$pur_row['pur_id']; 

        $category = $pur_row['pur_category'];
        $categories = explode(',',$category);
        $lenght = count($categories);
        //var_dump($category);

        $est_amou = $pur_row['pur_amount'];
        $est_amount = explode(',',$est_amou);
        var_dump($est_amount);
        //echo $ans_count = array_sum($est_amount);

        //echo $value = array_sum(array_column($est_amount,'pur_amount'));   

        $sum = array();
        foreach ($categories as $key => $sub_array) {
            echo $sub_array;
            foreach ($est_amount as $sub_key => $value) {

                echo $value;
                //If array key doesn't exists then create and initize first before we add a value.
                //Without this we will have an Undefined index error.
                if( ! array_key_exists($sub_key, $sum)) 
                    $sum[$sub_key] = 0;
                //Add Value
                $sum[$sub_key]+=$value;
            }
        }
        print_r($sum);

        for($i=0; $i< $lenght; $i++)
        { 
            $x++;
            $tot = $tot + $est_amount[$i];  
           // $balance = $estimation - $tot;
        } 
    } 
}  
?>

我的数据库如下所示