致命错误：未捕获异常'PDOException'，消息'SQLSTATE [HY000]：常规错误'.. C：\ xampp \ .. PDOStatement-> fetch（）..在第83行

I have actually seen similar questions on this "Fatal error: Uncaught exception 'PDOException'". But I have not been able to use have I have seen to resolve the challenge am having.

Below the code and the error message

<?php 
$sql5 = " set @rownum := 0; 
set @sum := 0;

select DISTINCT(ROUND(the_avg,4))
 FROM (
    select water_level, 
@rownum := (@rownum + 1) as rownum, 
@sum := IF(@rownum mod 7 = 1,0 + water_level,@sum + water_level) as running_sum,
IF(@rownum mod 7 = 0,@sum / 7,NULL) as the_avg
FROM " .$table." WHERE record_month_year = '".$startDateReport."'
order by id ASC
) s ";
$result5 = $db->prepare($sql5);
$result5->execute();
while ($rowReport = $result5->fetch(PDO::FETCH_ASSOC)) {
    ?>
    <tr style="font-size:11px;">
        <td><?php echo $rowReport['the_avg'] ; ?></td>
        </tr>
        <?php 
        }
        ?>

The line 83 is :

while ($rowReport = $result5->fetch(PDO::FETCH_ASSOC)) {

error:

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error' in C:\xampp\htdocs\awos\includes\loadboreholedatareport.php:83 Stack trace: #0 C:\xampp\htdocs\awos\includes\loadboreholedatareport.php(83): PDOStatement->fetch() #1 C:\xampp\htdocs\awos\borData-report.php(46): include('C:\xampp\htdocs...') #2 {main} thrown in C:\xampp\htdocs\awos\includes\loadboreholedatareport.php on line 83.

You can only do one query at a time with PDO.. Do them separately, like this..

   $db->query("set @rownum := 0"); 
    $db->query("set @sum := 0");
    $sql5 = "select DISTINCT(ROUND(the_avg,4))
     FROM (
        select water_level, 
    @rownum := (@rownum + 1) as rownum, 
    @sum := IF(@rownum mod 7 = 1,0 + water_level,@sum + water_level) as running_sum,
    IF(@rownum mod 7 = 0,@sum / 7,NULL) as the_avg
    FROM " .$table." WHERE record_month_year = '".$startDateReport."'
    order by id ASC
    ) s ";

And the rest would be the same.