Question

对于那些熟悉本书的人，我正在阅读本书“Luke Welling Laura Thomson第四版的PHP和MySQL Web开发”第751页。但是，书中提供的解决方案是使用MySQLi DB Connector，在测试时可以正常工作。我想对我的一个使用PHP PDO Connector的项目采用这个解决方案，但是我遇到了一个问题，试图得到与教科书相同的结果。我正在寻求一些帮助来转换MySQLi连接器来处理PDO过程。这两个例子都使用MySQL DB。我不确定我做错了什么并且寻求帮助。

我正在尝试让我的PDO过程在子id上为扩展数组生成相同的结果，就像原始教科书数组一样。

// Example taken from the text book
function expand_all(&$expanded) {
    // mark all threads with children as to be shown expanded
    $conn = db_connect();
    $query = "select postid from header where children = 1";
    $result = $conn->query($query);
    $num = $result->num_rows;
    for($i = 0; $i<$num; $i++) {
        $this_row = $result->fetch_row();
        $expanded[$this_row[0]]=true;
    }
}

// The print_r form the text book example looks like this:
// result:
mysqli_result Object (  [current_field] => 0 [field_count] => 1 
                        [lengths] => [num_rows] => 3 [type] => 0 
                      ) 

// expended:
   Array ( [0] => 1 ) Array ( [0] => 2 ) Array ( [0] => 4 ) 

//--------------------------------------------------------------//

// Know, here is my new adopted changes for using PHP PDO connector  
function expand_all(&$expanded)
{
    // mark all threads with children to be shown as expanded
    $table_name = 'header';
    $num = 1; 

    $sql = "SELECT postid FROM $table_name WHERE children = :num";

    try
    {
        $_stmt = $this->_dbConn->prepare($sql);
        $_stmt->bindParam(":num", $num, PDO::PARAM_INT);
        $_stmt->execute();

        $result  = $_stmt->fetchAll(PDO::FETCH_ASSOC);          

        // get the $expanded children id's
        foreach ($result as $key => $value) 
        { 
            foreach ($value as $k => $val)
            {
                $expanded[$k] = $val;
            }
        }
        return $extended;
    }
    catch(PDOException $e)
    {
        die($this->_errorMessage = $e);
    }

    //close the database  
    $this->_dbConn = null;          
}

// The print_r for the result looks like this:
 Array ( [0] => Array ( [children_id] => 1 ) 
         [1] => Array ( [children_id] => 2 ) 
         [2] => Array ( [children_id] => 4 ) 
        ) 

// The return extended print_r for the children id's
// look like this:
    Array ( [children_id] => 4);

Answer 1

您正在使用PDO::FETCH_ASSOC，因为每个结果都具有相同的列名，所以您将覆盖循环每次迭代的值。

如果你希望$ exapnded成为一组id，你需要调整你的循环，或者你应该使用PDO::FETCH_COLUMN。

使用循环调整：

   foreach ($result as $key => $value) 
    { 
        foreach ($value as $k => $val)
        {
            $expanded[] = $val;
        }
    }
    return $expanded;

使用提取模式调整：

    $_stmt = $this->_dbConn->prepare($sql);
    $_stmt->bindParam(":num", $num, PDO::PARAM_INT);
    $_stmt->execute();

    $result  = $_stmt->fetchAll(PDO::FETCH_COLUMN, 0);

    // at this point im not sure whay you are both passing 
    // $expanded by reference and returning it...
    // if you want to overwrite this array just do $expanded = $result
    // if you need to add these items TO an existing $expanded you can use
    // $expanded = array_merge($expanded, $result)

这两种方法都会给你一个像：

这样的数组

Array(
  0 => 1,
  1 => 2,
  2 => 4
)

如何将MySQLi连接器转换为PHP PDO

1 个答案: