How to (properly) chain multiple sequential MSSQL queries in Node - node.js

Question

I'm writing a simple nodejs CLI tool while learning promises (to avoid callback hell), and every tutorial/stackoverflow example I've found only shows how to make a single call. My use case is as follows:
1. Connect to the Database (this I can do)
2. Perform a SQL select statement (also got this part)
3. Do some stuff with the results
4. Repeat steps 2 & 3 a few more times
I'm collecting the MSSQL user name and password (with hard-coded server 'localhost' and database name 'testdb') so when the app executes I can't just jump into the MSSQL connection.
I can get this via callbacks, but right now I have about 50 queries so you can imagine the ugliness. The full code below does get me the first query, and I strongly suspect I'm not passing the "pool" object to the next "then", but when I try
.then((pool,result) => {
//next command
})
It still doesn't recognize pool
Here is the code (index.js):
const mssql = require('mssql');
const qry1 = "select fieldA from tblA";
const qry2 = "select fieldB from tblB";
const qry3 = "select fieldC from tblC";
var dbuser = '';
var dbpass = '';
var config = {}
function init() {
log('Beginning Audit');
collectDbInfo(); //The reason I don't just included it all here
}
function collectDbInfo() {
//code is irrelevant to the problem, this is where I'm collecting the database credentials
}
function start() {
config = {
user: dbuser,
password: dbpass,
server: 'localhost',
database: 'testdb'
}
mssql.connect(config)
.then(pool => {
//FIRST query
return pool.request().query(qry1)
})
.then(result => {
processQryA(result);
//SECOND query
return pool.request().query(qry2)
})
.then(result => {
processQryB(result);
//THIRD query
return pool.request().query(qry3)
})
.then(result => {
processQryC(result);
})
mssql.on('error',err => {
log('SQL Error:' err)
mssql.close();
process.exit(0);
}
}
processQryA(data) {
console.log(data.recordset[0].fieldA)
}
processQryB(data) {
console.log(data.rcordset[0].fieldB)
}
processQryC(data) {
console.log(data.recordset[0].fieldC)
}
init();
I fully appreciate I may be approaching this all wrong, so any advice or especially examples would be greatly appreciated.

Answer 1

If the queries are absolutely sequential in nature, you can achieve that with async/await:
async function start(){
config = {
user: dbuser,
password: dbpass,
server: 'localhost',
database: 'testdb'
}
try {
pool = await mssql.connect(config);
const res1 = await pool.request().query(qry1);
processQryA(res1);
const res2 = await pool.request().query(qry2);
processQryB(res2);
const res3 = await pool.request().query(qry3);
processQryC(res3);
const res4 = await pool.request().query(qry4);
processQryD(res4);
/*..And so on with rest of sequential queries*/
/*Any of them resulting in error will be caught in (catch)*/
} catch (error) {
console.error("Error in start()::", error);
}
}
Also: I would probably have my pool getting method separately from query executions to handle errors/validations nicely.