Writing multiple sql queries in nodejs - mysql

Question

I want to display all the values from two tables from my database and display it as console.log. If I write a single query in var sql and display it as console.log(results) it works but not for multiple queries.
var express = require('express');
var app = express();
let mysql = require('mysql')
let connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: '',
database: 'pitch_perfect_db2',
multipleStatements: true
})
app.get('/',(req, res) => {
connection.connect();
var sql = 'SELECT * FROM investors?; SELECT * FROM member_info?;'
connection.query(sql, function(err, results, fields){
if (!err) {
// res.send(JSON.stringify(results[0]));
// res.send(JSON.stringify(results[1]));
console.log('hey');
//console.log(results);
console.log(results[0]);
console.log(results[1]);
} else{
console.log('Error while performing query.');
}
});
connection.end();
})
//app.listen(port, () => console.log('Server Started pn port ${port}'));
app.listen(3002);

Answer 1

I was able to get it to work but I had to do 2 things:
First I renamed the tables to remove the question mark as it was always getting translated to a '1' and the table name no longer matched what was in the DB.
Second, I added an array to the connection.query(). After that it worked just fine.
More info here
var express = require('express');
var app = express();
let mysql = require('mysql')
let connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: '',
database: 'pitch_perfect_db2',
multipleStatements: true
})
app.get('/',(req, res) => {
connection.connect();
var sql = 'SELECT * FROM investors; SELECT * FROM member_info;';
//var sql = 'SELECT * FROM investors;';
connection.query(sql, [1, 2], function(err, results, fields){
if (!err) {
res.send(JSON.stringify(results[0]) + JSON.stringify(results[1]));
console.log('hey');
//console.log(results);
console.log(results[0]);
console.log(results[1]);
} else{
console.log('Error while performing query.');
console.log(err);
}
});
connection.end();
})
//app.listen(port, () => console.log('Server Started pn port ${port}'));
app.listen(3002);

Answer 2

In node you don't use ; in your sql statements. Assuming both the investors and member_info tables have the same number of columns, you will need to use this:
var sql = 'SELECT * FROM investors UNION ALL SELECT * FROM member_info';
Alternatively, if investors and member_info are unrelated tables, you will need to journey into callback hell to get what you need:
app.get('/',(req, res) => {
connection.connect();
var sql1 = 'SELECT * FROM investors';
var sql2 = 'SELECT * FROM member_info?';
connection.query(sql1, function(err, investors){
if (err) throw err; //you should use this for error handling when in a development environment
console.log(investors); //this should print
connection.query(sql2, function(err, members) {
if (err) throw err;
console.log(members);
res.render('your view', {investors:investors, members:members});
});
});
});
If you decide on the latter approach, I would urge you to reconsider your database layout.
If either of the tables in your examples have a foreign key relation with each other, you should definitely be using some kind of JOIN statement on these tables, instead of a UNION.