foreach $ _POST as $ value create

I just started learning PHP and I am having some difficulties with some of the coding. Hopefully, someone could help me a little.

I'm using this:

if(!empty($_POST['yyy'])) {
    foreach($_POST['yyy'] as $a1) {
echo " $a1";}}

The echo will write several results of $a1 depending on how many were selected in the form. What I want is to save those results to some values so I can add them in MySQL.

Something like this:

if(!empty($_POST['yyy'])) 
{
    foreach($_POST['yyy'] as $a1) 
{
echo " $a1";  where $a1 will create a $result1,$result2,$result3(for each isset)
}
}

Then if I use:

echo "$result2"; 

it will give me the second result.

Not clear whether you are asking about this kind of result or not. But you can use an array to store each values inside the foreach loop.

var data=[];// define an array to access outside of if statement later..
if(!empty($_POST['yyy'])) {
    foreach($_POST['yyy'] as $a1){
     data[]=$a1;
    //or can use array_push() method 
    array_push(data,$a1);
    }
}
/*this will give the second result(because array indexing starts from 0. So to get third result 
use data[2])*/

echo data[1];

Furthermore by echoing quoted variable will not give the value of that variable but gives a string literal.

echo "$result2"  //output---> $result