PHP for each loop returns only last element

Question

I'm trying to save data from an array by using foreach but it's only saving the last element of the array every time.

Here is my code:

public function demo($cakeId, $percent) {
    $query = $this->dbh->prepare("SELECT price, price * $percent / 100 as dprice FROM prices WHERE cake_id = ? ");
    $query->execute(array($cakeId));

    $prices = $query->fetchAll(\PDO::FETCH_ASSOC);      
    foreach ($prices as $key => $value) {
        $d_amount    = $value['dprice'];
        $price       = $value['price'];
        $final_price = $price - $d_amount;
    }

    $query2 = $this->dbh->prepare("UPDATE prices SET discount_price = ? WHERE cake_id = ?");
    $query2->execute(array($final_price,$cakeId));

    $return['data']    = [];
    $return['message'] = "Discount Added";
    $return['msgType'] = true;
    return $return;
}

$prices is an array containing all the prices but when I use $prices in a loop it only returns the last element.

Please help me on solving this.

Possible duplicate of Are PHP variables declared inside a foreach loop destroyed and re-created at each iteration? — Pyromonk
– Pyromonk, Commented Jun 9, 2017 at 9:18
@UtpalSarma how many prices updated in single row? now there are no coding issue you have to check on your logic side too — Ahmed Ginani
– Ahmed Ginani, Commented Jun 9, 2017 at 9:52

B. Desai · Accepted Answer · 2017-06-09 09:40:48Z

1

What I can see from your code It is not the issue or error of PHP or Mysql. Its issue of your logic i.e.:

foreach ($prices as $key => $value) {
         $xx = $value;

         $query2 = $this->dbh->prepare("UPDATE prices SET discount_price = ?");
         $query2->execute(array( $xx)); 
    }

The update statment execute each and every time and replace all price of table. So you are getting last updated value which replace all previous update statements

answered Jun 9, 2017 at 9:40

B. Desai

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4 Comments

Utpal Sarma Over a year ago

if i write the insert code outside the loop then $xx value is becomes null

B. Desai Over a year ago

what exactly you want. show us an example with database

Utpal Sarma Over a year ago

Thanks bro.. you are right issue is in my logic. Finally Solved it.

mickmackusa Over a year ago

There is no reason to declare the prepare() inside the loop -- it never changes, but is designed to be used over and over.

Omis Brown · Accepted Answer · 2017-06-09 09:21:13Z

0

$xxis created before any iteration and set to null. During each iteration if will be overwritten. It will not be destroyed at any time before leaving the scope of your script, function, method, ...

$xx;
foreach ($prices as $key => $value) {
         $xx = $value;
         $query2 = $this->dbh->prepare("UPDATE prices SET discount_price = ?");
         $query2->execute(array( $xx)); 
    }

answered Jun 9, 2017 at 9:21

Omis Brown

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1 Comment

mickmackusa Over a year ago

There is no reason to declare the prepare() inside the loop -- it never changes, but is designed to be used over and over.

Ahmed Ginani · Accepted Answer · 2017-06-09 09:25:30Z

0

For php variable declare inside loop you have to check this Are PHP variables declared inside a foreach loop destroyed and re-created at each iteration? for your issue.

Also another thing you should check your array is not empty before loop :

And you have to add condition for your update query check some good stuff for mysql :

$xx; 
if(!empty($prices)){
foreach ($prices as $key => $value) {
         $xx = $value;
         $query2 = $this->dbh->prepare("UPDATE prices SET discount_price = ?");
         $query2->execute(array( $xx)); 
    }
}

answered Jun 9, 2017 at 9:25

Ahmed Ginani

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2 Comments

Utpal Sarma Over a year ago

declare it but still the last element is getting saved

mickmackusa Over a year ago

There is no reason to declare the prepare() inside the loop -- it never changes, but is designed to be used over and over.

Krunal Limbad · Accepted Answer · 2017-06-09 09:35:48Z

0

I Guess You Can do is That use $key

$key is a Indexing of Array Values in $prices Array

foreach ($prices as $key => $value) {
         $query2 = $this->dbh->prepare("UPDATE prices SET discount_price = ?");
         $query2->execute(array($value[$key])); 
    }

Hope This Helps.

edited Jun 9, 2017 at 9:35

answered Jun 9, 2017 at 9:30

Krunal Limbad

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1 Comment

mickmackusa Over a year ago

There is no reason to declare the prepare() inside the loop -- it never changes, but is designed to be used over and over.

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