###导入

const Koa = require('koa');

const Router = require('koa-router');

const mysql = require('mysql');

const co = require('co-mysql');

###创建

let server = new Koa();

let router = new Router();

server.listen(8081);

server.use(async (ctx,next)=>{

  ctx.set('Access-Control-Allow-Origin', '*');

  await next();

});

###数据库 创建配置项

let conn = mysql.createPool({

  host:'localhost',

  user:'root',

  password:'',

  database:'houdunwang'

});

###放入 co中

server.context.db = co(conn);

###服务器选择主路由

server.use(router.routes())

#####路由路径，执行什么样的 sql语句

// 这些都是 省

router.get('/sheng',async ctx=>{

  let data = await ctx.db.query('SELECT * FROM city WHERE type = 1');

  ctx.body = data;

});

// 这些 都是市区

router.get('/city/:pid',async ctx=>{

  let {pid} = ctx.params;

  let data = await ctx.db.query('SELECT * FROM city WHERE pid=?',pid);

  ctx.body = data;

});