PDO duplicate values in array

Question

I need to get some currency ids from db, this is my code

$arr = [];

$currency_codes = array("USD", "RUB");
$currency_codes_in = implode(',', array_fill(0, count($currency_codes), '?'));
$query = "SELECT `curr_id` FROM `dictionary_currency` WHERE `curr_code` IN (". $currency_codes_in .")";
$stmt = $db->prepare($query); 
foreach ($currency_codes as $k => $id) {
    $stmt->bindValue(($k+1), $id);
}

$stmt->execute();
$currencies = $stmt->fetchAll();

foreach($currencies as $currency)
{
    foreach($currency as $key => $value)
    {
        $arr[] = $value;
    }
}
print_r($arr);
exit();

this is $currencies array

Array
(
    [0] => Array
        (
            [curr_id] => 643
            [0] => 643
            [curr_code] => RUB
            [1] => RUB
        )

    [1] => Array
        (
            [curr_id] => 840
            [0] => 840
            [curr_code] => USD
            [1] => USD
        )

)

and this is $arr

Array
(
    [0] => 643
    [1] => 643
    [2] => 840
    [3] => 840
)

I don't understand why I get duplicate values in arrays and how to prevent it?

Which key you want from $currencies array?

Apb
– Apb

2016-04-05 08:32:29 +00:00
Commented Apr 5, 2016 at 8:32 — Apb
– Apb, Commented Apr 5, 2016 at 8:32

Your Common Sense · Accepted Answer · 2016-04-05 11:51:33Z

2

PDO is a database wrapper that can do many things for you. For example,

bind input values right in execute()
get you returned data already in the desired format

So in fact you need two times less code than you have now:

$currency_codes = array("USD", "RUB");
$currency_codes_in = implode(',', array_fill(0, count($currency_codes), '?'));
$query = "SELECT `curr_id` FROM `dictionary_currency` WHERE `curr_code` IN ($currency_codes_in)";
$stmt = $db->prepare($query); 
$stmt->execute($currency_codes);
$arr = $stmt->fetchAll(PDO::FETCH_COLUMN);

or I would rather propose to make it like

$query = "SELECT curr_code, curr_id FROM dictionary_currency WHERE `curr_code` IN ($currency_codes_in)";
$stmt = $db->prepare($query); 
$stmt->execute($currency_codes);
$arr = $stmt->fetchAll(PDO::FETCH_KEY_PAIR);

edited Apr 5, 2016 at 11:51

answered Apr 5, 2016 at 11:30

Your Common Sense

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1 Comment

Heidel Over a year ago

Thanks a lot for help!

Severino Lorilla Jr. · Accepted Answer · 2016-04-05 09:24:28Z

1

The loop is problematic:

foreach($currencies as $currency) {
     foreach($currency as $key => $value) {
           $arr[] = $value;
     }
}

Just use a simple

foreach($currencies as $currency) {
    $arr[] = $currency[0];
}

Edit #1:

Using your $currencies and old query, I got the following:

Array
(
    [0] => Array
    (
        [curr_id] => 643
        [0] => 643
        [curr_code] => RUB
        [1] => RUB
    )

    [1] => Array
    (
        [curr_id] => 840
        [0] => 840
        [curr_code] => USD
        [1] => USD
    )
)

Array
(
    [0] => 643
    [1] => 643
    [2] => RUB
    [3] => RUB
    [4] => 840
    [5] => 840
    [6] => USD
    [7] => USD
)

edited Apr 5, 2016 at 9:24

answered Apr 5, 2016 at 8:32

Severino Lorilla Jr.

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2 Comments

Heidel Over a year ago

Thank you, it works! but I still don't understand why I get duplicate values in arrays (

Severino Lorilla Jr. Over a year ago

are you sure with your dump? using your old query, $arr should have the values USD and RUB as well.. checkout my dump using your $currencies data.. @Heidel

Phuoc Nguyen · Accepted Answer · 2018-09-16 08:03:03Z

0

I know this question is getting old. But here is the solution to prevent the duplicate values from PDO. Just using this:

$stmt->fetchAll(PDO::FETCH_ASSOC);

Instead of this:

$stmt->fetchAll();

answered Sep 16, 2018 at 8:03

Phuoc Nguyen

1

Comments

Hitesh Dabhi · Accepted Answer · 2016-04-05 08:33:15Z

-1

use following query $query = "SELECT DISTINCT curr_id FROM dictionary_currency WHERE curr_code IN (". $currency_codes_in .")";

answered Apr 5, 2016 at 8:33

Hitesh Dabhi

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