How to fetch multiple row value which contains multiple value separated by comma into a single array in php using pdo mysql

Question

I have a database table name books. Now I need to fetch value from multiple row values (column name position) which contains multiple value separated by comma. Now I need to fetch values from multiple rows into an array using pdo php.

<?php
require_once "includes\config.php";

$sql = 'SELECT * FROM books WHERE shelf_no=2';
$stmt = $db->prepare($sql);
$stmt->execute();
$row = $stmt->fetchALl(PDO::FETCH_ASSOC);
$d = array();
foreach ($row as $value) {
$d[] = explode(",",$value['position']);
}

print_r($d);
?>

and the result is

Array (
  [0] => Array (
    [0] => b1 
    [1] => b2 
  ) 
  [1] => Array ( 
    [0] => a2 
    [1] => a3
  )
)

But I need all values in a single array, like this:

Array ( [0] => b1 [1] => b2 [2] => a2 [3] => a3 )

Answer 1

You are exploding it (creating a new array) and then adding that array to another array.

You could run through each value in the exploded string and add them:

<?php
require_once "includes\config.php";

$sql = 'SELECT * FROM books WHERE shelf_no=2';
$stmt = $db->prepare($sql);
$stmt->execute();
$row = $stmt->fetchALl(PDO::FETCH_ASSOC);
$d = array();
foreach ($row as $value) {
    $temp = explode(",",$value['position']);
    foreach($temp as $pos){
        array_push($d, trim($pos));
    }   
}

print_r($d);
?>

If there are duplicates they will show though.

Answer 2

You can also replace your

$d[] = explode(",",$value['position']);

with

array_merge($d, explode(',', $value['position']));

That will make one array rather than an array of arrays. More info on array_merge at php.net.

A lot of PHP functions are more performant than the equivalent written in PHP. Ie this may be faster than a nested foreach loop. As always, if this is important to you, time both ways.