PHP: MySQLi Wrapper Class

mysqli_wrapper_class.php

<?php
/**
 * MySQLi Wrapper Class 0.1
 *
 * @author		qyang
 *
 */

class DBi
{

	/**
	 * @var string The resulttype of mysqli result, defualt is MYSQLI_ASSOC, use setResultType() to change.
	 */
	private $resultType = MYSQLI_ASSOC;

	/**
	 * @var string Warning message
	 */
	public $message = '';

	private $_db;
	private $_result;

	/**
	 * Creates the MySQLi object for usage.
	 *
	 * @param	array $config Required connection params.
	 */
	public function  __construct($config) {
		$this->_db = new mysqli($config['host'], $config['user'], $config['pass'], $config['table']);

		if ( $this->_db == false ) 
		{
			throw new Exception($this->_db->error, $this->_db->errno);
		}
	}
	
	/** 
	* Set the mysqli_result resulttype
	*
	* @param 	string resulttype, default is MYSQLI_ASSOC
	*/
	public function setResultType($type)
	{
		$type = strtoupper($type);
		if( in_array($type, array('MYSQLI_NUM', 'MYSQLI_ASSOC', 'MYSQLI_BOTH') )
		{
			$this->resultType = $type;
			return true;
		}
		else
		{
			$this->message = "Unknown resulttype {$type}.";
			$this->errno = 1;
			return false;
		}
	}

	/**
	 * Check if table exists
	 *
	 * @param string table name
	 * @return boolean
	 */
	public function table_exists($table)
	{
		$this->query("SHOW TABLES LIKE '{$table}");
		if( $this->_result->num_rows == 1 )
		{
			return true;
		}
		else
		{
			return false;
		}
	}

	/**
	 * Get table checksum
	 *
	 * @param string table name
	 * @return integer checksum of the table
	 */
	public function table_checksum($table)
	{
		$this->query("CHECKSUM TABLE {$table}");
		$row = $this->_result->fetch_assoc();
		
		return $row['Checksum'];
	}

	/**
	 * Do the query
	 *
	 * @param	string sql statement
	 * @return	null
	 */
	public function query($sql)
	{
		$this->sql = $this->_db->real_escape_string($sql);
		$this->_result = $this->_db->query($sql);

		if ( !$this->_result )
		{
			throw new Exception( $this->_db->error, $this->_db->errno );
		}
	}

	/**
	 * Get the result
	 *
	 * @param	none
	 * @return  array
	 */
	public function result()
	{
		/* grab all data */
		$data = array();

		while ( $row = $this->_result->fetch_array($this->resultType) )
		{
			$data[] = $row;
		}

		$this->_result->free();

		return $data;
	}

	/**
	 * Returns the auto_increment insert id
	 * This MUST come after an insert query.
	 */
	public function id()
	{
		return $this->_db->insert_id;
	}

	/**
	 * destruct class
	 */
	public function __destruct()
	{
		$this->_db->close();
	}

}