存数据
boolean Driver_Cache_Driver_Database::set( string/array $key [, $data $value = null , $lifetime $lifetime = integer 3600 ] )
参数列表
参数 类型 描述 默认值 $keystring/array支持多存 $value$dataValue 多存时此项可空 null $lifetime$lifetime有效期,默认3600,即1小时,0表示不限制 integer 3600 
boolean public function set($key, $value = null, $lifetime = 3600)
{
    if (IS_DEBUG)Core::debug()->info($key, 'database cache set key');
    if ($lifetime>0)
    {
        $lifetime += TIME;
    }
    if (is_array($key))
    {
        foreach ($key as $k=>$v)
        {
            $k = $this->prefix . $k;
            if (is_numeric($v))
            {
                $data = array
                (
                    md5($k),
                    $k,
                    '',
                    $v,
                    $lifetime,
                );
            }
            else
            {
                $this->_format_data($value[$k]);
                $data = array
                (
                    md5($k),
                    $k,
                    $value[$k],
                    0,
                    $lifetime,
                );
            }
            $this->_handler->values($data);
        }
    }
    else
    {
        $key = $this->prefix . $key;
        if (is_numeric($value))
        {
            # 对于数值型数据,存在number字段里
            $data = array
            (
                md5($key),
                $key,
                '',
                $value,
                $lifetime,
            );
        }
        else
        {
            $this->_format_data($value);
            $data = array
            (
                md5($key),
                $key,
                $value,
                0,
                $lifetime,
            );
        }
        $this->_handler->values($data);
    }
    $rs = $this->_handler->columns(array('key', 'key_string', 'value', 'number', 'expire'))->replace($this->tablename);
    if ($rs[0])
    {
        return true;
    }
    else
    {
        return false;
    }
}