mysql - Node Express MySql Sql 查询不起作用

Question

我是 Node Express 的新手，我尝试通过一些教程来学习它

下面的代码段工作正常显示

Express server is running under port no : 3000 DB connection succeded.

const mysql = require("mysql");
const express = require('express');
var app = express();
const bodyparser = require('body-parser');

app.use(bodyparser.json());


var mysqlConnection = mysql.createConnection({
    host:'localhost', 
    user:'root',
    password:'',
    database:'employeedb'
});

mysqlConnection.connect((err)=>{
  if(!err)
  console.log('DB connection succeded.');
  else
  console.log('DB connection failed \n Error : '+ JSON.stringify(err,undefined,2));
});

app.listen(3000,()=>console.log('Express server is running under port no : 3000'));

然后我尝试运行下面的代码段

app.get('/ab',(req,res)=>{
    console.log("test1");
  mysqlConnection.query('SELECT * FROM employee',(err,rows,fields)=>{
     console.log("test2");  
     if (!err){
     console.log(rows);
      res.send(rows);
  }
     else{
     console.log(err);
   }
  })

console.log("test3");

});

问题是浏览器需要很长时间才能显示响应并显示

localhost didn’t send any data. ERR_EMPTY_RESPONSE

但在终端中只打印了test1和test3

据我所知，如果存在错误，应该显示错误。不是这样吗？但是在这里，没有显示任何错误。请帮我解决这个错误

Answer 1

你试过调用get请求然后连接数据库吗？

app.get('/ab',(req,res)=>{
  mysqlConnection.connect((err)=>{
    if(!err){
      console.log('DB connection succeded.');
      mysqlConnection.query('SELECT * FROM employee',(err,rows,fields)=>{
          console.log("test2");  
...