Mysqli php数组索引

$row = $overview_response->fetch_array(MYSQLI_NUM);

returns the following as an array:

Array ( [0] => 12 [1] => username [2] => email [3] => a53ccb24bfb1135eb45e675464f948 [4] => Test message [5] => 1 [6] => Test subject [7] => 2016-01-29 15:35:02 )

How could i access the parameters like only the username?

Been testing the following before:

foreach ($row as $key) {
    echo $key[1];
}

Your $row is an array so you can walk through the values using foreach(). However the values of your array are not arrays.

so this command echo $key[1] is invalid as it tries to access the first element of $key but $key is a string.

You can get to your values by using something like:

$id = $row[0];
$username = $row[1];
// and so on 

Your code

$row = $overview_response->fetch_array(MYSQLI_NUM);

returns to you an array. You can access key in array by it's index. I suppose username is value with key 1.

$row = $overview_response->fetch_array(MYSQLI_NUM);
var_dump($row[1]);

This is the simpliest way.

Other way can be using MYSQLI_ASSOC constant, which will return string keys instead of numeric keys:

$row = $overview_response->fetch_array(MYSQLI_ASSOC);
var_dump($row);
// after that you can still access username by key, 
// but now it will be the name of a corresponding field
var_dump($row['username']);   // if field is called `username`