Mine

/**
 * Gets specified or all data from the user database.
 *
 * @param array, string $fields
 * @return instance
 */
function get($fields = NULL)
{
	// Select all fields if none specified
	if (!$fields) $fields = '*';
	// Select an array of fields from a $fields
	elseif (is_array($fields)) $fields = implode(', ', $fields);
	// Select only one field
	else $this->field = $fields;

	// Create select statement
	$this->sql = "SELECT $fields FROM $this->user_table AS t1 ";

	return $this;
}

/**
 * Gets specified or all data from the user database joined with the group database.
 *
 * @param array, string $fields
 * @return instance
 */
function get_group($fields = NULL)
{
	// Select all fields (from the left table, t1) if none specified
	if (!$fields) $fields = '*';
	// Select an array of fields from a $fields
	elseif (is_array($fields)) $fields = implode(', ', $fields);
	// Select only one field
	else $this->field = $fields;

	// Create select statement
	$this->sql = "
			SELECT t2.$fields
				FROM users AS t1
					LEFT JOIN user_groups AS t2
						ON (t1.user_group_id = t2.user_group_id)
	";

	return $this;
}

/**
 * Narrows the scope of a get*() call to only the specified email
 *
 * @param unknown_type $email
 * @return instance
 */
function where_email($email)
{
	// Create where statement
	$this->sql .= "WHERE t1.email = '$email' ";

	return $this;
}


/**
 * Executes a specified query and returns either a result array, row array, or single column.
 *
 * @param string $result_type
 * @return array, bool, string
 */
function execute($result_type = 'result_array')
{
	// Execute the query
	$this->query = $this->db->query($this->sql);

	// Returns false if no rows resulted from the query
	if ($this->query->num_rows() == 0) return FALSE;
	// Returns a string if this is only one column
	else
	{
		switch ($result_type)
		{
			case 'result_array':
				return $this->query->result_array();
				break;
			case 'row_array':
				return $this->query->row_array();
				break;
			case 'string':
				$array = $this->query->row_array();
				return $array[$this->field];
		}
	}

	// Unset the transfered field;
	unset($this->field);
}