Updating MySQL table with PHP and checkboxes in WordPress - php

Question

On my website enter link description here I'm using checkbox buttons for updating data in a MySql table (pages are with login) and use this code in PHP that's working fine:
<?php
$sql="SELECT *,cast(DATE_FORMAT(datum,'%d-%m-%Y ') AS CHAR(32)) as datum FROM wedstrijden";
$result=mysqli_query($db,$sql);
$count=mysqli_num_rows($result);
?>
<table style="width: 100%;">
<tr>
<td><form name="frmactive" action="1fanionchange.php" method="post">
<tr>
<td colspan="6"><input name="activate" type="submit" id="activate" value="Open selected" />
</tr>
<tr>
<td> </td>
</tr><tr>
<td align="center"><!--<input type="checkbox" name="allbox" title="Select or Deselct ALL" style="background-color:#ccc;"/> --></td>
<td align="center"><strong>Id</strong></td>
<td align="center"><strong>Datum</strong></td>
<td align="center"><strong>Uur</strong></td>
<td align="center"><strong>Thuis</strong></td>
<td align="center"><strong>Uit</strong></td>
</tr>
<?php
while($rows=mysqli_fetch_array($result)){
?>
<tr>
<td align="center"><input name="checkbox[]" type="checkbox" id="checkbox[]" value="<? echo $rows['id']; ?>"></td>
<td align="center"><? echo $rows['id']; ?></td>
<td align="center"><? echo $rows['datum']; ?></td>
<td align="center"><? echo $rows['uur']; ?></td>
<td align="center"><? echo zoeknaam($rows['thuisploeg']); ?></td>
<td align="center"><? echo zoeknaam($rows['uitploeg']); ?></td>
</tr>
<?php
}
?>
<tr>
<td colspan="6"><input name="activate" type="submit" id="activate" value="Open selected" />
</tr>
</form>
</td>
</tr>
</table>
But when I use the same code in WordPress (I'm trying to make the website in WordPress), it is not working and no records are displayed. When I try to find the number of rows using:
echo $count. "<br />";
I get the correct number of records in that table. But the records are not showed?
Any idea how to handle the problem? Thanks.
PS. I use the plugin phpexec in WordPress!

Answer 1

In WordPress it is suggested to use the WordPress builtin Queries. So that it can have maximum compatibility with the server too it is hosted.
Reference: https://codex.wordpress.org/Class_Reference/wpdb
global $wpdb;
And all the following functions will attach the database that is defined as global..
$wpdb->insert('wp_submitted_form', array(
'name' => 'Kumkum',
'email' => 'kumkum#gmail.com',
'phone' => '3456734567', // ... and so on
));
Like wise you can use it for Update / Select as per your wish and it is considered as the best one according to WordPress..