Global connection already exists. Call sql.close() first - sql-server

Question

I'm trying to build a node.js backend,I have a usecase that i should connect everytime to the server and not to the database ,see one of the webservices:
router.get('/CriticalityGraph/:server/:user/:password/:database/', function(req, res, next) {
user = req.params.user;
password = req.params.password;
server = req.params.server;
database = req.params.database;
criticalityState=req.params.criticalityState
// config for your database
var config = {
user: user,
password: password,
server: server,
database:database
};
sql.connect(config, function (err) {
var request = new sql.Request();
request.query("SELECT MachineName, alarmState, criticality FROM MachineTable  ORDER BY criticality DESC"
, function (err, recordset) {
if (err) console.log(err);
else {
for(i=0;i<recordset.recordsets.length;i++) {
res.send(recordset.recordsets[i])
}
sql.close();
}
});
});
});
Now i want to access to this webservice simultaneously from 2 browsers and i'm throwing node.js Global connection already exists. Call sql.close() first.
Any suggestions to fix the problem?

Answer 1

Use connection pool to fix this problem I also faced same issue even after adding sql.close()
Use below connection pool code to fix this issue.
new sql.ConnectionPool(config).connect().then(pool => {
return pool.request().query("")
}).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();
});