来自表单输入的数组 - Select 语句 MySQLi 参数化

Question

将在表单输入中输入的短语转换为数组，以使用 MySQLi 传递到 MySQL select 语句 where 子句中。 php 代码我已经实现了这一点，但我无法锻炼如何参数化查询以防止 sql 注入攻击。我看过这个网站上的几个问题，但我很难将它与我的代码联系起来。

if(!empty($_POST['Message']))
{
      $searchStr = get_post($con,'Message');
      $aKeyword = explode(" ", $searchStr);

      $query ="SELECT m.ID, m.MessageText FROM MessageMain m LEFT OUTER JOIN Likes l on m.ID = l.PostID WHERE MessageText LIKE '%" . $aKeyword[0] . "%'";

     for($i = 1; $i < count($aKeyword); $i++) {
        if(!empty($aKeyword[$i])) {
            $query .= " OR MessageText like '%" . $aKeyword[$i] . "%'";
        }
      }

      $query .= " GROUP BY m.ID, m.MessageText ORDER BY count(m.id) desc";

       $result = $con->query($query);
       $rowcount=mysqli_num_rows($result);

Answer 1

如果您想根据要匹配的关键字数量动态构建 WHERE 子句，您可以这样做：

if (!empty($_POST['Message'])) {
    $searchStr = get_post($con, 'Message');
    $aKeyword = explode(" ", $searchStr);

    $whereClauseArr = [];
    foreach ($aKeyword as $keyword) {
        if ($keyword) {
            $whereClauseArr[] = "MessageText LIKE ?";
            $whereValues[] = '%'.$keyword.'%';
        }
    }

    $stmt = $con->prepare(
        'SELECT m.ID, m.MessageText 
        FROM MessageMain m 
        LEFT OUTER JOIN Likes l on m.ID = l.PostID 
        WHERE '.implode(' OR ', $whereClauseArr).'
        GROUP BY m.ID, m.MessageText ORDER BY count(m.id) desc'
    );

    $stmt->bind_param(str_repeat('s', count($whereValues)), ...$whereValues);
    $stmt->execute();
    $result = $stmt->get_result();
}

尽管在您的情况下，使用正则表达式可能会更好地根据多个值检查同一列。这将使您的查询更简单，并且可能更快，具体取决于您拥有的关键字数量。

if (!empty($_POST['Message'])) {
    $searchStr = get_post($con, 'Message');
    $aKeyword = explode(" ", $searchStr);

    $aKeyword = array_filter($aKeyword); // Remove empty values

    $stmt = $con->prepare(
        'SELECT m.ID, m.MessageText 
        FROM MessageMain m 
        LEFT OUTER JOIN Likes l on m.ID = l.PostID 
        WHERE MessageText REGEXP ?
        GROUP BY m.ID, m.MessageText ORDER BY count(m.id) desc'
    );

    $regexString = implode('|', $aKeyword);
    $stmt->bind_param('s', $regexString);
    $stmt->execute();
    $result = $stmt->get_result();
}

来自表单输入的数组 - Select 语句 MySQLi 参数化

Array from Form Input - Select Statement MySQLi Parameterisation

php

mysqli

sql-injection