Node Express Multiple SQL server Connection - sql-server

Question

I need to connect to diferent databases on direfent servers.
The servers are Microsoft SQL Server.
I do it like this:
dbconfig.js
var sql1 = require('mssql')
var sql2 = require('mssql')
var conn1 = {server:"SERVER IP", database:"db1", user:"foo", password:"foo", port:1433}
var conn2= {server:"SERVER2 IP", database:"db2", user:"foo2", password:"foo2", port:1433}
var server1= sql1.connect(conn1)
.then(function() { debug('Connected'); })
.catch(function(err) { debug('Error connect SQL Server', err); });
var server2= sql2.connect(conn2)
.then(function() { debug('Connected'); })
.catch(function(err) { debug('Error connect SQL Server', err); });
module.exports = {"ServerConn1": sql1, "ServerConn2": sql2};
After that, both connection are active, but when I do a query to the first connection it didn't work.
The error is Invalid object name 'FooDatabase.dbo.fooTable'.
Can anyone help me to solve this issue?
Thanks!

Answer 1

I implement using MySQL you can do the same thing mssql by passing empty database parameter and letter update database before creates connection.
And you do not need to import two-times just update the DB name before creating connection or query.
const express =
require('express');
const app = express();
const port = process.env.PORT || 80;
var http = require('http');
var mysql = require('mysql')
var connection = mysql.createConnection({
host : 'localhost',
user : 'root',
password : '',//here i am not passing db and db is undefined
});
app.get('/db1',function(req,res)
{
connection.config.database="task" //here i updating db name before query
connection.query('SELECT * FROM tasks', function (error, results, fields) {
console.log(results)
res.json(fields)
connection.end()
})
})
app.get('/db2',function(req,res)
{
connection.config.database="cg_taskview" //db2
connection.query('SELECT * FROM tasks', function (error, results, fields) {
if (error)
console.log(error);
console.log(results)
res.json(fields)
});
connection.end()
})
var server = http.createServer(app);
server.listen(port, function () {
})

Answer 2

Below is my code for the testing:
var sql = require('mssql/msnodesqlv8');
const config = {server:'localhost', database:'TestDB',
options: { trustedConnection: true }};
const config2 = {server:'SomewhereNotExist', database:'TestDB',
options: { trustedConnection: true }};
(async () => {
try {
let pool = await sql.connect(config);
let result = await pool.request().query('select count(1) as cnt from AlarmWithLastStatus');
console.log('DB1 result:');
console.dir(result.recordset);
let pool2 = await sql.connect(config2);
let result2 = await pool2.request().query('select count(1) as cnt from AlarmWithLastStatus');
console.log('DB2 result:');
console.dir(result2.recordset);
} catch (err) {
if (err) console.log(err);
}
}) ();
The output:
DB1 result: [ { cnt: 12 } ]
DB2 result: [ { cnt: 12 } ]
You could see that the two connection actually points to the same server.
If you change the second query to a table that does not exist in this server, that will generate the error you got.

Answer 3

I started experiencing a similar problem when a second MSSQL server was added as a data source to the project ... Fortunately, I found a solution in the examples for tediousjs.
Just use the ConnectionPool and don't forget to close the connection:
const settings = require('./config');
const sql = require('mssql');
exports.someSqlQuery = async function(sqlQuery) {
const cPool = new sql.ConnectionPool(config);
cPool.on('error', err => console.log('---> SQL Error: ', err));
try {
await cPool.connect();
let result = await cPool.request().query(sqlQuery);
return {data: result};
} catch (err) {
return {error: err};
} finally {
cPool.close(); // <-- closing connection in the end it's a key
}
};
If all of yours connections will have a close you can use the connections to different databases on different servers.