将数据库连接到节点js表示出现连接错误

Question

将我的节点js程序连接到sql server之后，出现以下错误：

  

“消息”：“连接丢失-套接字挂断”，       “ code”：“ ESOCKET”

我应该在节点js代码中添加或更改什么？

我的nodejs代码如下：

var express = require("express");
var bodyParser = require("body-parser");
var sql = require("mssql");
var app = express(); 

app.use(bodyParser.json()); 
app.use(function (req, res, next) {

  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, 
  contentType,Content-Type, Accept, Authorization");
  next();
});

var server = app.listen(process.env.PORT || 1433, function () {
  var port = server.address().port;
  console.log("App now running on port", port);
});

var dbConfig = {
  user:  "sa",
  password: "Chetu@123",
  server: "localhost",
  database:"sample"
};

var  executeQuery = function(res, query){             
   sql.connect(dbConfig, function (err) {
       if (err) {   
                 console.log("Error while connecting database :- " + err);
                 res.send(err);//this line is running 
              }
              else {
                     var request = new sql.Request();
                     // query to the database
                     request.query(query, function (err, res) {
                       if (err) {
                                  console.log("Error while querying database :- " + err);
                                  res.send(err);
                                 }
                                 else {
                                   res.send(res);
                                        }
                           });
                   }
      });           
}

//GET API
 app.get("/api/user", function(req , res){
            var query = "select * from [Student]";
            executeQuery (res, query);
 });