//数据库备份
    public function backups()
    {
        //1.获取数据库信息
        $info = Db::getConfig();
        $dbname = $info['database'];
        //2.获取数据库所有表
        $tables = Db::query("show tables");
        //3、组装头部信息
        header("Content-type:text/html;charset=utf-8");
        $path = './data/';
        $database = $dbname;   //获取当前数据库
        $info  = "-- ----------------------------\r\n";
        $info .= "-- 日期：".date("Y-m-d H:i:s",time())."\r\n";
        $info .= "-- MySQL - 5.7-MariaDB : Database - ".$database."\r\n";
        $info .= "-- ----------------------------\r\n\r\n";
        $info .= "SET NAMES utf8;\r\nSET FOREIGN_KEY_CHECKS = 0;\r\n\r\n";
        //4、检查目录是否存在
        if (is_dir($path)) {
            if (is_writable($path)) {
            } else {
                echo '目录不可写'; exit();
            }
        } else {
            mkdir($path,0777,true);
        }
        //5、保存的文件名称
        $file_name = $path.$database.'_'.date('Ymd_His').'.sql';
        file_put_contents($file_name, $info, FILE_APPEND);
        //6、循环表，写入数据
        foreach ($tables as $k => $v) {
            $val = $v["Tables_in_$database"];
            $sql = "SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='$val' AND TABLE_SCHEMA='$dbname'";
//            $sql = "SELECT * FROM ".$val;
            $res = Db::query($sql);
            $tableStatus = Db::query("SHOW TABLE STATUS FROM `{$res[0]['TABLE_SCHEMA']}` WHERE name = '{$res[0]['TABLE_NAME']}'");
            $eng = strtolower($tableStatus[0]['Engine']);

            //查询表结构
            $info_table = "-- ----------------------------\r\n";
            $info_table .= "-- Table structure for `$val`\r\n";
            $info_table .= "-- ----------------------------\r\n\r\n";
            $info_table .= "DROP TABLE IF EXISTS `$val`;\r\n";
            if (count($res) < 1) {
                continue;
            }
            $info_table .= "CREATE TABLE `$val` (\n\r\t";
            foreach ($res as $kk => $vv) {
                $info_table .= " `".$vv['COLUMN_NAME']."` ";
                $info_table .= $vv['COLUMN_TYPE'];
                //是否允许空值
                if ($vv['IS_NULLABLE'] == 'NO') {
                    $info_table .= " NOT NULL ";
                }
                //判断主键
                if ($vv['EXTRA']) {
                    $info_table .= " AUTO_INCREMENT ";
                    $key = $vv['COLUMN_NAME'];
                }
                //编码
//                if ($vv['CHARACTER_SET_NAME']) {
//                    $info_table .= " CHARACTER SET ".$vv['CHARACTER_SET_NAME'];
//                }
                //字符集
                if ($vv['COLLATION_NAME']) {
                    $info_table .= " COLLATE ".$vv['COLLATION_NAME'];
                }
                //默认数值
                if ($vv['COLUMN_DEFAULT']) {
                    $info_table .= " DEFAULT ".$vv['COLUMN_DEFAULT'];
                }
                //注释
                if ($vv['COLUMN_COMMENT']) {
                    $info_table .= " COMMENT '".$vv['COLUMN_COMMENT']."',\n\r\t";
                }else{
                    $info_table .= ",\n\r\t";
                }
            }
            $info_table .= " PRIMARY KEY (`$key`) USING BTREE";
            $info_table .= "\n\r) ENGINE={$eng} AUTO_INCREMENT=212 DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC;\r\n\r\n";

            //查询表数据
            $info_table .= "-- ----------------------------\r\n";
            $info_table .= "-- Data for the table `$val`\r\n";
            $info_table .= "-- ----------------------------\r\n\r\n";
            file_put_contents($file_name,$info_table,FILE_APPEND);
            $sql_data = "select * from $val";
            $data = Db::query($sql_data);
            $count= count($data);
            if ($count < 1) {
                continue;
            }
            foreach ($data as $key => $value) {
                $sqlStr = "INSERT INTO `$val` VALUES (";
                foreach($value as $v_d){
                    $v_d = str_replace("'","\'",$v_d);
                    $sqlStr .= "'".$v_d."', ";
                }
                //需要特别注意对数据的单引号进行转义处理
                //去掉最后一个逗号和空格
                $sqlStr = substr($sqlStr,0,strlen($sqlStr)-2);
                $sqlStr .= ");\r\n";
                file_put_contents($file_name,$sqlStr,FILE_APPEND);
            }
            $info = "\r\n";
            file_put_contents($file_name,$info,FILE_APPEND);
        }
        //7、下载数据到本地
        ob_end_clean();
        header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
        header('Content-Description: File Transfer');
        header('Content-Type: application/octet-stream');
        header('Content-Length: ' . filesize($file_name));
        header('Content-Disposition: attachment; filename=' . basename($file_name));
        readfile($file_name);
        DownloadFile($path.$file_name);
        echo "数据已备份";
    }