php - PHP 中的 MySQL 访问类

Question

我有一个 MySQL 连接类，如下所示:

class MySQLConnect
{
    private $connection;
    private static $instances = 0;

    function __construct()
    {
        if(MySQLConnect::$instances == 0)
        {
            //Connect to MySQL server
            $this->connection = mysql_connect(MySQLConfig::HOST, MySQLConfig::USER, MySQLConfig::PASS)
                or die("Error: Unable to connect to the MySQL Server.");
            MySQLConnect::$instances = 1;
        }
        else
        {
            $msg = "Close the existing instance of the MySQLConnector class.";
            die($msg);
        }
    }

    public function singleQuery($query, $databasename)
    {
        mysql_select_db(MySQLConfig::DB, $this->connection)
            or die("Error: Could not select database " . MySQLConfig::DB . " from the server.");
        $result = mysql_query($query) or die('Query failed.');
        return $result;
    }

    public function createResultSet($query, $databasename)
    {
        $rs = new MySQLResultSet($query, MySQLConfig::DB, $this->connection ) ;
        return $rs;
    }

    public function close()
    {
        MySQLConnect::$instances = 0;
        if(isset($this->connection) ) {
                mysql_close($this->connection) ;
                unset($this->connection) ;
        }
    }

    public function __destruct()
    {
        $this->close();
    }
}

MySQLResultSet 类如下所示:

class MySQLResultSet implements Iterator
{
    private $query;
    private $databasename;
    private $connection;
    private $result;

    private $currentRow;
    private $key = 0;
    private $valid;

    public function __construct($query, $databasename, $connection)
    {
        $this->query = $query;
        //Select the database
        $selectedDatabase = mysql_select_db($databasename, $connection)
            or die("Error: Could not select database " . $this->dbname . " from the server.");
        $this->result = mysql_query($this->query) or die('Query failed.');
        $this->rewind();
    }

    public function getResult()
    {
        return $this->result;
    }

//  public function getRow()
//  {
//      return mysql_fetch_row($this->result);
//  }

    public function getNumberRows()
    {
        return mysql_num_rows($this->result);
    }

    //current() returns the current row
    public function current()
    {
        return $this->currentRow;
    }

    //key() returns the current index
    public function key()
    {
        return $this->key;
    }

    //next() moves forward one index
    public function next()
    {
        if($this->currentRow = mysql_fetch_array($this->result) ) {
            $this->valid = true;
            $this->key++;
        }else{
            $this->valid = false;
        }
    }

    //rewind() moves to the starting index
    public function rewind()
    {
        $this->key = 0;
        if(mysql_num_rows($this->result) > 0) 
        {
            if(mysql_data_seek($this->result, 0) ) 
            {
                $this->valid = true;
                $this->key = 0;
                $this->currentRow = mysql_fetch_array($this->result);
            }
        }
        else
        {
            $this->valid = false;
        }
    }

    //valid returns 1 if the current position is a valid array index
    //and 0 if it is not valid
    public function valid()
    {
        return $this->valid;
    }
}

以下类是我如何访问数据库的示例:

class ImageCount
{
    public function getCount()
    {
        $mysqlConnector = new MySQLConnect();
        $query = "SELECT * FROM images;";
        $resultSet = $mysqlConnector->createResultSet($query, MySQLConfig::DB);
        $mysqlConnector->close();
        return $resultSet->getNumberRows();
    }
}

我像这样使用 ImageCount 类:

if(!ImageCount::getCount())
{
    //Do something
}

问题:这是访问数据库的好方法吗？如果效果不好，有人可以推荐一种替代方法吗？

谢谢。

Answer 1

嘿，Mike，实现您自己的类来处理数据库连接没有任何问题，到目前为止您所拥有的都很好，但是 PHP 已经提供了一个用于处理数据库连接的接口(interface)，无论您连接到哪个数据库管理器。我建议你看一下http://www.php.net/manual/en/book.pdo.php因为它几乎具有处理查询、语句、结果集、错误等所需的所有功能。

干杯，米。