node.js 全局连接已经存在.首先调用 sql.close() [英] node.js Global connection already exists. Call sql.close() first

问题描述

我正在尝试使用来自 sql server 数据库的 node.js 创建 web 服务，在前端，当我同时调用这两个 web 服务时，它抛出一个错误全局连接已经存在.先调用sql.close().

I'm trying to create web services using node.js from an sql server database,in the frontend when i call those 2 webservices simultaneously it throws an error Global connection already exists. Call sql.close() first .

任何解决方案?

var express = require('express');
var router = express.Router();
var sql = require("mssql");

router.get('/Plant/:server/:user/:password/:database', function(req, res, next) {

    user = req.params.user;
    password = req.params.password;
    server = req.params.server;
    database = req.params.database;


    // config for your database
    var config = {
        user: user,
        password: password,
        server: server,
        database:database

    };

    sql.connect(config, function (err) {



        // create Request object
        var request = new sql.Request();

        // query to the database and get the records
        request.query("SELECT  distinct PlantName FROM MachineryStateTable"
            , function (err, recordset) {

                if (err) console.log(err)
                else {

                    for(i=0;i<recordset.recordsets.length;i++) {
                        res.send(recordset.recordsets[i])
                    }

                }
               sql.close();

            });

    });

});





router.get('/Dep/:server/:user/:password/:database/:plantname', function(req, res, next) {

    user = req.params.user;
    password = req.params.password;
    server = req.params.server;
    database = req.params.database;
    plantname = req.params.plantname;

    // config for your database
    var config = {
        user: user,
        password: password,
        server: server,
        database:database

    };

    sql.connect(config, function (err) {



        // create Request object
        var request = new sql.Request();

        // query to the database and get the records
        request.query("SELECT  distinct DepName FROM MachineryStateTable where PlantName= '"+plantname+"'"
            , function (err, recordset) {

                if (err) console.log(err)
                else {

                    for(i=0;i<recordset.recordsets.length;i++) {
                        res.send(recordset.recordsets[i])

                    }
                    sql.close();
                }

            });
    });
});



module.exports = router;

推荐答案

你必须创建一个 poolConnection试试这个:

You have to create a poolConnection try this:

new sql.ConnectionPool(config).connect().then(pool => {

  return pool.request().query("SELECT * FROM MyTable")

  }).then(result => {

    let rows = result.recordset
    res.setHeader('Access-Control-Allow-Origin', '*')
    res.status(200).json(rows);
    sql.close();

  }).catch(err => {

    res.status(500).send({ message: `${err}`})
    sql.close();

  });

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