mysql> GRANT ALL PRIVILEGES ON *.* TO jiqing@"%" IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.03 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
這兩條指令的作用，是創建用戶jiqing,密碼是123456。所有ip都可以訪問。並授予這個用戶所有的權限，刷新生效。
同時在/etc/hosts中，將阿里雲的mysql地址加入其中。
127.0.0.1 rm-wz94y9juv07017s60.mysql.rds.aliyuncs.com
關於hosts，我們本機有hosts，路由中也有hosts，路由中設置了hosts，就相當於所有的電腦都設置了。
jiqing@ubuntu:/usr/local/nginx/conf/vhost$ ping jiqing.sheep.5hao.com
PING jiqing.sheep.5hao.com (192.168.199.126) 56(84) bytes of data.
64 bytes from jiqing.hotel.caomall.net (192.168.199.126): icmp_seq=1 ttl=64 time=0.047 ms
64 bytes from jiqing.hotel.caomall.net (192.168.199.126): icmp_seq=2 ttl=64 time=0.052 ms
64 bytes from jiqing.hotel.caomall.net (192.168.199.126): icmp_seq=3 ttl=64 time=0.052 ms
64 bytes from jiqing.hotel.caomall.net (192.168.199.126): icmp_seq=4 ttl=64 time=0.052 ms
jiqing@ubuntu:/usr/local/nginx/conf/vhost$ ping local.sheep.5hao.com
PING local.sheep.5hao.com (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.057 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.052 ms
64 bytes from localhost (127.0.0.1): icmp_seq=3 ttl=64 time=0.050 ms
64 bytes from localhost (127.0.0.1): icmp_seq=4 ttl=64 time=0.053 ms
這兩個都是路由中的hosts設置的，如果我把自己本地的jiqing.sheep.5hao.com更改成192.168.199.127。看看效果。
jiqing@ubuntu:/usr/local/nginx/conf/vhost$ ping jiqing.sheep.5hao.com
PING jiqing.sheep.5hao.com (192.168.199.127) 56(84) bytes of data.
From jiqing.hotel.caomall.net (192.168.199.126) icmp_seq=1 Destination Host Unreachable
From jiqing.hotel.caomall.net (192.168.199.126) icmp_seq=2 Destination Host Unreachable
From jiqing.hotel.caomall.net (192.168.199.126) icmp_seq=3 Destination Host Unreachable
From jiqing.hotel.caomall.net (192.168.199.126) icmp_seq=4 Destination Host Unreachable
會發現，如果ping不通，它就會去路由中找。
再次改為127.0.0.1
jiqing@ubuntu:/usr/local/nginx/conf/vhost$ ping jiqing.sheep.5hao.com
PING jiqing.sheep.5hao.com (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.056 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.051 ms
64 bytes from localhost (127.0.0.1): icmp_seq=3 ttl=64 time=0.047 ms
64 bytes from localhost (127.0.0.1): icmp_seq=4 ttl=64 time=0.052 ms
64 bytes from localhost (127.0.0.1): icmp_seq=5 ttl=64 time=0.046 ms
會發現，如果ping通了，就優先執行本地的ip。很有意思。
這樣就可以實現，同樣的代碼。可以連接本地的數據庫。即便上傳到了服務器，一樣可以正常使用。
這其實是造假吧，訪問的並不是阿里雲的mysql數據庫，而是本地的數據庫。
線上的服務器，也要這么造假，訪問的也不是阿里雲的數據庫，而是它自己的數據庫。
經過這樣造假之后，本地和線上的數據庫配置就都不需要更改了。
'DB_HOST' => 'rm-wz94y9juv07017s60.mysql.rds.aliyuncs.com', // 數據庫host
'DB_NAME' => 'xxx', // db name
'DB_USER' => 'jiqing', // 用戶名
'DB_PWD' => '123456', // 密碼