php - 错误日志中的错误PHP警告: Invalid argument supplied for foreach()

Question

错误日志中有错误，但结果显示得很完美，我不知道如何以及为什么在错误文件中显示此错误。

PHP警告:为foreach()提供了无效的参数，请为此提供帮助。如何摆脱此错误？

<?php

    $business_name = $value['business_name'];
    $sql = "SELECT * FROM listings_reviews WHERE business_name = '$business_name' order by listing_date DESC";
    $result = $conn -> query($sql);

    while ($row = $result->fetch_assoc()) {
      $data[] = $row;
    }

    //print_r($row); //exit;
    ?>


    <?php
    foreach ($data as $value){ ?>

    <div class="col-md-12 reviews">
    <span style="color:#000"><?php echo hide_mail ($value['reviewer_email'])?></span>&nbsp;&nbsp;
    <span style="color:#000">
    <?php

    $starNumber = $value['rating'];

    //echo $starNumber; exit;

        for($x=1;$x<=$starNumber;$x++) {
            echo '<i style="font-size:12px; color:#00BF9A" class="fa fa-star" aria-hidden="true"></i>';
        }
        if (strpos($starNumber,'.')) {
            echo '<i style="font-size:12px; color:#00BF9A" class="fa fa-star-half-o" aria-hidden="true"></i>';
            $x++;
        }
        while ($x<=5) {
            echo '<i style="font-size:12px; color:#00BF9A" class="fa fa-star-o" aria-hidden="true"></i>';
            $x++;
        }
    ?>
    </span> 

    <span style="float:right; color:#666; font-size:14px"><?php echo $value['listing_date']?></span>
    <hr style="margin:5px">
    <span style="color:#666"><?php echo $value['comment']?></span>





    </div>
    <?php
    }  

    ?>

Answer 1

在某些情况下，没有结果，因此永远不会调用$data[] = $row;且未定义$data。

解决方法是正确初始化$data:

$data = []; // add this

while ($row = $result->fetch_assoc()) {
    $data[] = $row;
}