php mysql 查询 fatal error

Question

我有这个 php 代码来填充一个表，其中一些数据进入 mysl 数据库，但是当我执行时它说

"Fatal error: Call to undefined method MysqlClass::query()"


<?php 
include "config.php"; 
$data = new Mysqlclass();
$data->connetti(); 
$post_sql = $data->query("SELECT * FROM products ORDER BY id DESC"); 
if(mysql_num_rows($post_sql) > 0) 
    {while($post_obj = $Data->estrai($post_sql))
        {$id=$post_obj->id; 
            $name = stripcslashes($post_obj->name); 
            $cat = stripcslashes($post_obj->category);
            $price= stripcslashes($post_obj->price);
            echo "<td>".$id."</td>";
            echo "<td>".$name."</td>";
            echo "<td>".$cat."</td>";
            echo "<td>".$price."</td>";
        }
    }else{
        echo"Tabella vuota";
    }
    $data->disconnetti();
?>

当我声明$Data->query时，错误出现在第2行。

也许函数查询不正确，我是 PHP 脚本新手。

我在教程中使用了这段代码。我不知道“query”和“estrai”(提取)键是否正确。

这是配置文件:

<?php

    class MysqlClass
    {
      private $nomehost = "localhost";     
      private $nomeuser = "root";          
      private $password = "xxxxx"; 
      private $nomedb = "intse";
      private $attiva = false;
      public function connetti()
      {
        if(!$this->attiva)
        {
          if($connessione = mysql_connect($this->nomehost,$this->nomeuser,$this->password) or die (mysql_error()))
          {
            $selezione = mysql_select_db($this->nomedb,$connessione) or die (mysql_error());
          }
        } else{
          return true;
        }
      } 
      public function disconnetti()
      {
        if($this->attiva)
        {
          if(mysql_close())
          {
            $this->attiva = false; 
            return true; 
          } else {
             return false; 
          }
        }
      }
    }  
    ?>

http://imageshack.com/a/img35/1966/pd0v.png所以现在我必须用数据库第二个条目填充 row2，用数据库第三个条目填充 row3，并增加 html 中的表行数以填充其他数据库条目。谢谢。

Answer 1

变量区分大小写，($Data->estrai);
使用$data->query将使用MysqlClass类中的查询方法，而不是系统预定义的方法，您需要为其编写一个。如果您想使用类中的方法，例如 $data->method()，则需要在类中构建它。例如

public function query($sql) {

    return mysql_query($sql);

}

此外，我看不到 $this->attiva 的用法，因为您没有在某处将其设置为 TRUE。$selezione 也没用。

更新:

mysql_select_db 仅返回一个 bool 值，除了报告失败选择(死亡)之外，您不需要它。
它应该是这样的(如果我没有犯任何语法错误..):

<?php 

include 'config.php'; 

$data = new MysqlClass();
$data->connetti();

$post_sql = $data->query("SELECT * FROM products ORDER BY id DESC"); 

if(mysql_num_rows($post_sql) > 0) {

    while($post_obj = $data->estrai($post_sql)) {

        // the data it returns is an array, not object
        // so it should be $post_obj['key'] not $post_obj->key

        $id = $post_obj['id'];
        $name = stripcslashes($post_obj['name']);
        $cat = stripcslashes($post_obj['category']);
        $price = stripcslashes($post_obj['price']);

        echo "<td>".$id."</td>";
        echo "<td>".$name."</td>";
        echo "<td>".$cat."</td>";
        echo "<td>".$price."</td>";
    }

} else {

    echo 'Tabella vuota';

}

$data->disconnetti();

?>

.

<?php

class MysqlClass {

    private $nomehost = 'localhost';     
    private $nomeuser = 'root';          
    private $password = 'xxxxx'; 
    private $nomedb = 'intse';
    private $attiva = FALSE;
    private $connessione;

    public function connetti() {

        if(!$this->attiva && ($this->connessione = mysql_connect($this->nomehost, $this->nomeuser, $this->password) or die(mysql_error()))) {

            mysql_select_db($this->nomedb, $this->connessione) or die(mysql_error());
            $this->attiva = TRUE; // Now this becomes useful, because the value has been set

        }

        return $this->attiva;

    } 

    // Method to build up the query

    public function query($sql) {

        return mysql_query($sql, $this->connessione);

    }

    // Method to extract information from the query

    public function estrai($query) {

        return mysql_fetch_array($query, MYSQL_ASSOC);

    }

    public function disconnetti() {

        // More straight forward way to return the status

        if($this->attiva) return mysql_close($this->connessione);

        return FALSE;

    }

}

更新2:

<?php 

include 'config.php'; 

$data = new MysqlClass();
$data->connetti();

$post_sql = $data->query("SELECT * FROM products ORDER BY id DESC"); 

echo '<table>';

if(mysql_num_rows($post_sql) > 0) {

    while($post_obj = $data->estrai($post_sql)) {

        // the data it returns is an array, not object
        // so it should be $post_obj['key'] not $post_obj->key

        $id = $post_obj['id'];
        $name = stripcslashes($post_obj['name']);
        $cat = stripcslashes($post_obj['category']);
        $price = stripcslashes($post_obj['price']);

        echo '<tr>';

        echo "<td>".$id."</td>";
        echo "<td>".$name."</td>";
        echo "<td>".$cat."</td>";
        echo "<td>".$price."</td>";

        echo '</tr>';

    }

} else {

    echo 'Tabella vuota';

}

echo '</table>';

$data->disconnetti();

?>