PHP - Most Likely Simple Fix, Script Doesn't Update Mysql Query.

I have created a registration page to access my website. After the user registrate himself should appear an alert saying that the registration was OK and a redirect to main.php page... however for some reason if I create an insert statement the alert and the redirect don't appear... If I remove the insert the alert and the redirect works... why?

This is part of the code of my 3 files:

registration.php (ajax call)

response.php (answer to ajax call)

data_access.php (the function works but doesn't permit alert and redirect to appear)

Can someone help me to fix the code? 

Hi, this query runs fine when I run it from PHPMyAdmin:
 

UPDATE `tran_term_taxonomy` SET `description` = (SELECT keyword from `good_keywords` ORDER BY RAND() LIMIT 1,1) WHERE `tran_term_taxonomy`.`taxonomy` = 'post_tag' AND `tran_term_taxonomy`.`description` = "" LIMIT 1

However, when I run the same query in a PHP file on my server, the page doesn't load at all. The message I get is: www.somesite.com is currently unable to handle this request. HTTP ERROR 500. This is my PHP code:

<?php 
include("/database/connection/path/db_connect.php"); 

$result4 = mysqli_query($GLOBALS["___mysqli_ston"], "UPDATE `tran_term_taxonomy` SET `description` = (SELECT keyword from `good_keywords` ORDER BY RAND() LIMIT 1,1) WHERE `tran_term_taxonomy`.`taxonomy` = 'post_tag' AND `tran_term_taxonomy`.`description` = "" LIMIT 1");
echo $result4;

?>

So how do I make this query work please? Thanks for your guidance.

I have a php script that I've been running that seems to have been working but now I'm wondering if some of my logic is potentially off.

I select records from a db table within a date range which I put into an array called ```$validCount```

If that array is not empty, that means I have valid records to update with my values, and if it's empty I just insert. The trick with the insert is that if the ```STORES```  is less than the ```Quantity``` then it only inserts as many as the ```STORES``` otherwise it inserts as many as ```Quantity```.

So if a record being inserted with had 

    Stores: 14 Quantity:12

Then it would only insert 12 records but if it had
  
    Stores:1  Quantity:20

It would only insert 1 record.

In short, for each customer I should only ever have as many valid records (within a valid date range) as they have stores. If they have 20 stores, I can have 1 or 2 records but should never have 30.

It seems like updating works fine but I'm not sure if it's updating the proper records, though it seems like in some instances it's just inserting too many and not accounting for past updated records.

This is the logic I have been working with:

  if(!empty($validCount)){
            for($i=0; $i<$row2['QUANTITY']; $i++){
                try{
                    $updateRslt = $update->execute($updateParams);
                }catch(PDOException $ex){
                    $out[] = $failedUpdate;
                }
            }
    }else{    
        if($row2["QUANTITY"] >= $row2["STORES"]){
            for($i=0; $i<$row2["STORES"]; $i++){     
                try{
                    $insertRslt = $insert->execute($insertParams);
                }catch(PDOException $ex){
                    $out[] = $failedInsertStore;
                }
            }
        }elseif($row2["QUANTITY"] < $row2["STORES"]){
            for($i=0; $i<$row2["QUANTITY"]; $i++){     
                try{
                    $insertRslt = $insert->execute($insertParams);
                }catch(PDOException $ex){
                    $out[] = $failedInsertQuantity;
                }
            }
        }
    }

Let's say customer 123 bought 4 of product A and they have 10 locations

    customerNumber  |  product  |  category  |  startDate  |  expireDate  | stores
    ----------------------------------------------------------------------------------
    123                 1           A           2018-08-01    2019-03-01      10
    123                 1           A           2018-08-01    2019-03-01      10
    123                 1           A           2018-08-01    2019-03-01      10
    123                 1           A           2018-08-01    2019-03-01      10

Because they purchased less than their store count, I insert 4 records. Now if my ```$validCheck``` query selects all 4 of those records (since they fall in a valid date range) and my loop sees that the array isn't empty, it knows it needs to update those or insert. Let's say they bought 15 this time. Then I would need to insert 6 records, and then update the expiration date of the other 9 records. 

    customerNumber  |  product  |  category  |  startDate  |  expireDate  | stores
    ----------------------------------------------------------------------------------
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10
    123                 1           A           2018-08-01    2019-03-11      10

There can only ever be a maximum of 10 (store count) records for that customer and product within the valid date range. As soon as the row count for that customer/product reaches the equivalent of stores, it needs to now go through and update equal to the quantity

so now I'm running this but it's not running and no errors, but it just returns back to the command line   

$total = $row2['QUANTITY'] + $validCheck;
    if ($total < $row2['STORES']) {
        $insert_count = $row2['QUANTITY'];
        $update_count = 0;
    } else {
        $insert_count = $row2['STORES'] - $validCheck; // insert enough to fill all stores
        $update_count = ($total - $insert_count); // update remainder
    }

        
    for($i=0; $i<$row2['QUANTITY']; $i++){
        try{
            $updateRslt = $update->execute($updateParams);
        }catch(PDOException $ex){
            $failedUpdate = "UPDATE_FAILED";
            print_r($failedUpdate);
            $out[] = $failedUpdate;
        }
    }
    
        
    for($i=0; $i<$insert_count; $i++){
        try{
            $insertRslt = $insert->execute($insertParams);
        }catch(PDOException $ex){
            $failedInsertStore = "INSERT_STORE_FAILED!!!: " . $ex->getMessage();
            print_r($failedInsertStore);
            $out[] = $failedInsertStore;
        }
    }```