创建并连接数据库，并修改登录和注册接口

node_modules/mysql2/lib/connection.js

@@ -0,0 +1,12 @@
+'use strict';
+
+const BaseConnection = require('./base/connection.js');
+
+class Connection extends BaseConnection {
+  promise(promiseImpl) {
+    const PromiseConnection = require('./promise/connection.js');
+    return new PromiseConnection(this, promiseImpl);
+  }
+}
+
+module.exports = Connection;