PHP、MySQL查询返回空数组，为什么？

Question

我已经被 MySQL 的 PHP/PDO 问题困扰了几天，我只是不明白为什么它返回一个空数组......

我收到的错误消息如下所示:

Notice: Undefined offset: 0 in /home/saxon/students/20141/jolf14/www/oophp/kmom04/webroot/sqltest3.php on line 24

Notice: Trying to get property of non-object in /home/saxon/students/20141/jolf14/www/oophp/kmom04/webroot/sqltest3.php on line 24

第一类看起来像这样:

<?php 

/** 
 * ctMovies is a class that handles movies and database 
 * 
 */ 
class ctMovies{ 
   
   /** 
   * Constructor 
   * 
   */ 
   public function __construct() { 
     
    } 
     
     

 /** 
 * Use the current querystring as base, modify it according to $options and return the modified query string. 
 * 
 * @param array $options to set/change. 
 * @param string $prepend this to the resulting query string 
 * @return string with an updated query string. 
 */ 
function getQueryString($options = array(), $prepend = '?') { 
    // parse query string into array 
    $query = array(); 
    parse_str($_SERVER['QUERY_STRING'], $query); 

    // Modify the existing query string with new options 
    $query = array_merge($query, $options); 

    // Return the modified querystring 
    return $prepend . htmlentities(http_build_query($query)); 
} 

/** 
 * Create links for hits per page. 
 * 
 * @param array $hits a list of hits-options to display. 
 * @param array $current value. 
 * @return string as a link to this page. 
 */ 
function getHitsPerPage($hits, $current = null) { 
    $nav = "Träffar per sida: "; 
    foreach ($hits AS $val) { 
        if ($current == $val) { 
            $nav .= "$val "; 
        } else { 
            $nav .= "<a href='" . $this->getQueryString(array('hits' => $val)) . "'>$val</a> "; 
        } 
    } 
    return $nav; 
} 

/** 
 * Create navigation among pages. 
 * 
 * @param integer $hits per page. 
 * @param integer $page current page. 
 * @param integer $max number of pages.  
 * @param integer $min is the first page number, usually 0 or 1.  
 * @return string as a link to this page. 
 */ 
function getPageNavigation($hits, $page, $max, $min = 1) { 
    $nav = ($page != $min) ? "<a href='".$this->getQueryString(array('page' => $min))."'>&lt;&lt;</a>" : '&lt;&lt;'; 
    $nav .= ($page > $min) ? "<a href='".$this->getQueryString(array('page' => ($page > $min ? $page - 1 : $min)))."'>&lt;</a>" : '&lt;'; 

    for ($i = $min; $i <= $max; $i++) { 
        if ($page == $i) { 
            $nav .= "$i "; 
        } else { 
            $nav .= "<a href='".$this->getQueryString(array('page' => $i)) ."'>$i</a> "; 
        } 
    } 

    $nav .= ($page < $max) ? "<a href='".$this->getQueryString(array('page' => ($page < $max ? $page + 1 : $max)))."'>&gt;</a>" : '&gt;'; 
    $nav .= ($page != $max) ? "<a href='".$this->getQueryString(array('page' => $max))."'>&gt;&gt;</a> " : '&gt;&gt; '; 
    return $nav; 
} 

/** 
 * Function to create links for sorting 
 * 
 * @param string $column the name of the database column to sort by 
 * @return string with links to order by column. 
 */ 
function orderby($column) { 
    $nav = "<a href='" . $this->getQueryString(array('orderby' => $column, 'order' => 'asc')) . "'>&darr;</a>"; 
    $nav .= "<a href='" . $this->getQueryString(array('orderby' => $column, 'order' => 'desc')) . "'>&uarr;</a>"; 
    return "<span class='orderby'>" .$nav . "</span>"; 
} 

}

第二个类扩展了第一个类，如下所示:

<?php 

/** 
 * cMovies is a class that handles movies and database 
 * 
 */ 
class cMovies extends ctMovies { 
   /** 
   * Properties 
   * 
   */ 
    private $db; 
    private $sqlOrig; 
    private $where; 
    private $groupby; 
    private $params;  
    
   /** 
   * Constructor 
   * 
   */ 
   public function __construct($db) { 
       parent::__construct(); 
     $this->db=$db; 
    } 
     
     


/** 
 * Function to get movie table 
 * 
 */ 
function getTable(){ 
// Get parameters  
$title = htmlentities(isset($_GET['title']) ? $_GET['title'] : null); 
$title=  str_replace('*', '%', $title); 
$hits = isset($_GET['hits']) ? $_GET['hits'] : 8; 
$page = isset($_GET['page']) ? $_GET['page'] : 1; 
$year1 = isset($_GET['year1']) && !empty($_GET['year1']) ? $_GET['year1'] : null; 
$year2 = isset($_GET['year2']) && !empty($_GET['year2']) ? $_GET['year2'] : null; 
$orderby = isset($_GET['orderby']) ? strtolower($_GET['orderby']) : 'id'; 
$order = isset($_GET['order']) ? strtolower($_GET['order']) : 'asc'; 


// Check that incoming parameters are valid 
is_numeric($hits) or die('Check: Hits must be numeric.'); 
is_numeric($page) or die('Check: Page must be numeric.'); 
is_numeric($year1) || !isset($year1) or die('Check: Year must be numeric or not set.'); 
is_numeric($year2) || !isset($year2) or die('Check: Year must be numeric or not set.'); 

// Prepare the query based on incoming arguments 
$this->sqlOrig = ' 
  SELECT  
    M.*, 
    GROUP_CONCAT(G.name) AS genre 
  FROM Movie AS M 
    LEFT OUTER JOIN Movie2Genre AS M2G 
      ON M.id = M2G.idMovie 
    INNER JOIN Genre AS G 
      ON M2G.idGenre = G.id 
'; 
$this->where = null; 
$this->groupby = ' GROUP BY M.id'; 
$limit = null; 
$sort = " ORDER BY $orderby $order"; 
$this->params= array(); 


// Select by title 
if ($title) { 
    $this->where .= ' AND title LIKE ?'; 
    $this->params[] = $title; 
} 

// Select by year 
if ($year1) { 
   $this->where .= ' AND year >= ?'; 
    $this->params[] = $year1; 
} 
if ($year2) { 
    $this->where .= ' AND year <= ?'; 
    $this->params[] = $year2; 
} 

// Pagination 
if ($hits && $page) { 
    $limit = " LIMIT $hits OFFSET " . (($page - 1) * $hits); 
} 


// Complete the sql statement 
$this->where = $this->where ? "WHERE 1 {$this->where}" : null; 
$sql = $this->sqlOrig . $this->where . $this->groupby . $sort . $limit; 
$res = $this->db->ExecuteSelectQueryAndFetchAll($sql, $this->params); 


//// Put results into a HTML-table 
$tr = "<tr><th>Rad</th><th>Id " . $this->orderby('id') . "</th><th>Bild</th><th>Titel " . $this->orderby('title') . "</th><th>År " . $this->orderby('year') . "</th><th>Genre</th></tr>"; 
foreach ($res AS $key => $val) { 
    $tr .= "<tr><td>{$key}</td><td>{$val->id}</td><td><img width='80' height='40' src='{$val->image}' alt='{$val->title}' /></td><td>{$val->title}</td><td>{$val->YEAR}</td><td>{$val->genre}</td></tr>"; 
} 
return $tr; 
} 
/** 
 * Function to get a result which can be used to calculate maximal number 
 * of pages.  
 */ 
function getResMaxPages() { 
//// Get max pages for current query, for navigation
$sql = 'SELECT COUNT(id) AS rows FROM ($this->sqlOrig $this->where $this->groupby) AS Movie';
echo "$this->sqlOrig";
echo "$this->where";
echo "$this->groupby";
$res = $this->db->ExecuteSelectQueryAndFetchAll($sql, $this->params);
return $res; 
} 
} 

这一切都是由这个小家伙经营的:

<?php

/** 
 * This is a joax pagecontroller. 
 * It handles movie information from a database 
 */ 
// Include the essential config-file which also creates the $joax variable with its defaults. 
include(__DIR__ . '/config.php'); 

$joax['stylesheets'][] = 'css/table.css'; 


// Connect to a MySQL database using PHP PDO 
$db = new cDatabase($joax['database']); 
$movies = new cMovies($db); 

$tr=$movies->getTable(); 
$hits = isset($_GET['hits']) ? $_GET['hits'] : 8; 
$page = isset($_GET['page']) ? $_GET['page'] : 1; 
$title = htmlentities(isset($_GET['title']) ? $_GET['title'] : null); 
$year1 = isset($_GET['year1']) && !empty($_GET['year1']) ? $_GET['year1'] : null; 
$year2 = isset($_GET['year2']) && !empty($_GET['year2']) ? $_GET['year2'] : null; 
$res=$movies->getResMaxPages();
$rows = $res[0]->rows;
$max = ceil($rows / $hits); 
// Do it and store it all in variables in the joax container. 
$joax['title'] = "Visa filmer med olika sökalternativ"; 

$hitsPerPage =  $movies->getHitsPerPage(array(2, 4, 8), $hits); 
$navigatePage = $movies->getPageNavigation($hits, $page, $max); 
//$sqlDebug = $db->Dump(); 

$joax['main'] = <<<EOD
<h1>{$joax['title']}</h1> 

<form> 
  <fieldset> 
  <legend>Sök</legend> 
  <input type=hidden name=hits value='{$hits}'/> 
  <input type=hidden name=page value='1'/> 
  <p><label>Titel (delsträng, använd * eller % ): <input type='search' name='title' value='{$title}'/></label></p> 
  <p><label>Skapad mellan åren:  
      <input type='text' name='year1' value='{$year1}'/></label> 
      -  
      <input type='text' name='year2' value='{$year2}'/> 
     
  </p> 
  <p><input type='submit' name='submit' value='Sök'/></p> 
  <p><a href='?'>Visa alla</a></p> 
  </fieldset> 
</form> 

<div> 
  <div>{$rows} träffar. {$hitsPerPage}</div> 
  <table> 
  {$tr} 
  </table> 
  <div class='center'>{$navigatePage}</div> 
</div> 

EOD;

// Finally, leave it all to the rendering phase of joax. 
include(JOAX_THEME_PATH);

我还有一个类来处理数据库，但它工作正常，我也可以发布它，但我没有从中得到任何错误，并且可以从数据库加载文件。

Answer 1

undefined offset :0 表示您引用的数组键不存在。尝试获取非对象的属性支持这一点，并且在 sqltest3.php 的第 24 行引用它之前，您可能无法正确实例化对象，如果您不发布代码，我无法真正帮助您对于该文件。在引用对象之前，您可能需要执行类似的操作:

$some_variable = new whatever_class_is_on_line_24_of_sqltest3_dot_php();