Can't fetch from two tables using php

Can't fetch from two tables using php
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#1

Hello could someone help me know what could be a ploblem. I am getting Warning: mysqli_query(): Couldn’t fetch mysqli error.

<?php 
// displaying list of regions and councils from database
$sql= "SELECT Regions.regioncode, Regions.regionname, Councils.councilcode, Councils.councilname FROM Regions INNER JOIN Councils ON Regions.regioncode = Councils.regioncode";
$result = mysqli_query($mysql_id,$sql);
if ($result->mysqli_num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
    	
    	echo "<tr"."id="."data".">".
    	"<td>".$row['Regions.regioncode']."</td>".
    	"<td>".$row['Regions.regionname']."</td>".
    	"<td>".$row['Councils.councilcode']."</td>".
    	"<td>".$row['Councils.councilname']."</td>".
		"</tr>";

    }
} else {
    echo "No region available";
}

// ending if statement

mysqli_close($mysql_id);

// end the connection after displaying the list of reports


echo "</table>";
?>
#2

Try:

while ($row = mysqli_fetch_array($r, MYSQLI_ASSOC))