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Variable undefined nodeJS MySQL query

I have a table with different post categories and I want to get the categories ID from the name. Example name: random => id: 1.
I got the variable like this:
const { name, title, cat, con, user_file } = req.body;
console.log(cat); //returnes the name as it should
This is my query:
var sql = "SELECT id FROM cat WHERE cat_name = ?";
db.query(sql, cat, function(err, result) {
if(!result){
return next();
}
const cat_id = result[0];
});
If I than try to console.log the cat_id I get undefined. I have tried doing this in many different way but it comes out the same every time. If I just run
SELECT id FROM cat WHERE cat_name = random
in thee database manager it works like it should and returnes the ID.
Edit: The purpose is to get the id to insert a foreign key into another table.

Your results is an empty array. This is (assuming you're using the mysql package) because your function call is incorrect.
When passing arguments to your query, as explained here, you need to pass an array of values, not just a single value. For example:
connection.query('SELECT * FROM `books` WHERE `author` = ?', ['David'], function (error, results, fields) {
// error will be an Error if one occurred during the query
// results will contain the results of the query
// fields will contain information about the returned results fields (if any)
});
In your case, that means you're looking for cats where the name is the first character of cat (e.g. cat[0]).

It ended up being a problem with variables only being saved in the query level. It console.logged the right number inside the db.query and the wrong one out of the db.query. So the solution for now is to put it inside I guess.
My solution now looks like this:
exports.post = (req, res, next) => {
let { cat } = req.body;
let cat_id = 0;
db.query(
"SELECT id FROM cat WHERE cat_name = ?",
[cat],
async function (err, results) {
if (!err) cat_id = results[0].id;
else console.log(err);
db.query(
"INSERT INTO posts SET ?",
{ cat_id: cat_id },
(error, results) => {
if (error) console.log(error);
else res.status(200).redirect("/post");
}
);
}
);
};

node.js + mysql: "Cannot enqueue Handshake after already enqueuing a Handshake."

I'm attempting to make two functions, one which retrives an object from an SQL database, the other which saves an object to the same SQL database. I am using node.js and mysql to do this. I have two functions, fetchEmployee and Employee.save, which fetch and save an employee respectively. When I call fetchEmployee, and the callback includes Employee.save, however, I get the error Cannot enqueue Handshake after already enqueuing a Handshake. Even weirder, Employee.save seems to run before the error is thrown.
EDIT: employee.save appearing to run is a symptom of async, as console.log("Saved!") is called before the callback function passed to SQL.parse This means the error appears during the parse. Further, if within parse console.log("connection created"); is added after con.connect, and console.log("Made it out."); is added after the end of con.connect, when calling Employee.save, the console outputs > "connection created", then throws the error, meaning the save query is never finished, but the error is thrown after con.connect
The Employee class is defined by the following
function Employee(obj) {
/** Defines the Employee class
* #arg obj.id : an integer; the employee's id
* #arg obj.name : A string; the employee's name
* #arg obj.position : A string; the employee's positions split by commas
*/
this.id = obj.id;
this.name = obj.name;
this.position = obj.position;
this.save = function() {
SQL.parse({
sql : `UPDATE EMPLOYEES
SET id=?, name=?, position=?
WHERE id=?`,
replace_ : [this.id, this.name, this.position, this.id],
result : false
});
console.log("Saved!");
}
}
Note the console.log("Saved!");, as this comes up later
fetchEmployee is defined by this function:
function fetchEmployee(id, callback) {
/** Fetch an employee from the employee table
* #arg id : An integer; the id of the employee to fetch
* #arg callback : A callback function to pass the employee to
*/
SQL.parse({ // Perform the parse, define the sql, replace, and result
sql : "SELECT * FROM employees WHERE id=?",
replace_ : [id],
result : true
},
function(err, data) {
if(err) { // Pass an error if there's an error
callback(err, null);
throw err;
}
// Pass the employee to the callback as an employee object if there's no errors
callback(null, new Employee({ // data is passed as a list from the sql table, so take only the object we need through [0]
id : data[0].id,
name : data[0].name,
position : data[0].position
})
);
});
}
Finally, SQL.parse is defined in this file:
var mySQL = require("mysql");
var con = mySQL.createConnection({ //Create connection
host : "localhost",
database : "testdb1",
user : "root",
password : "***************"
});
function parse(obj, callback) {
/** Parses an sql query.
* #arg callback : A callback function, will be passed the data
* #arg obj.sql : an sql query
* #arg obj.replace_ : A list of replacements for ?s in sql
* #arg obj.result : a boolean indicating whether a result should be returned
*/
//Assign meaningfull values
obj.replace_ = obj.replace_ || [];
callback = callback || function() {};
con.connect(function(err) {
if(err) throw err;
//Connect and pass the sql command to the server
con.query(obj.sql, obj.replace_, function(err, data) {
if(err) { //Pass the err to the callback if there is an err
callback(err, null);
throw err;
}
else if(obj.result) { // Pass the data to the callback if result is true
callback(null, data)
}
});
});
}
module.exports = {
parse : parse
};
When I call this block of code
fetchEmployee(985, function(err, data) {
if(err) throw err;
console.log(data);
data.save();
});
The console outputs
Employee {
id: 985,
name: 'Skidd',
position: 'Dishwasher, Busser',
save: [Function] }
Saved!
Error: Cannot enqueue Handshake after already enqueuing a Handshake. [...]
It appears to me that it correctly runs fetchEmployee, as data is logged to the console correctly with the data of the employee. It then logs Saved!, seeming to indicate that Employee.save ran correctly, then after all the code is done, throws the error. I can't for the life of me figure out why this would happen, here or on google or through testing.
I've tried to add con.end to the end of parse in sql.js, this changes the error to Cannot enqueue Handshake after invoking quit

I was able to solve this problem by placing
var con = mySQL.createConnection({ //Create connection
host : "localhost",
database : "testdb1",
user : "root",
password : "***************"
});
inside of the parse function, though I'm not 100% sure why this worked.

I followed what the previous person did and it worked for me too.
I guess the problem was the connection was being made asynchronously.
putting this inside the promise solved the problem

When retrieving data from sql, i want to use the where condition as a variable

I am writing code in conjunction with sql on node js.
I want to load the data according to the condition, and I want to dynamically get the condition depending on the variable.
Here is the current code:
db.all ("select CollectionID, CollectionName from Collection where
CollectionID = abc", function () {
How do I want to receive data according to the variable abc ?
abc's value is number .

var abc = 1;
var query = 'select CollectionID, CollectionName from Collection where CollectionID = ?'
db.all (query, [abc], function (err, rows) {
if (err) throw err;
console.log(rows);
});

node mysql not executing query

I'm having trouble executing my update query. Right now it's inside the select query witch works fine, the update queries are well formed, since I can copy paste a single update query from the output and it will update accordingly. no errors thrown, stream with update string appear but none are executed.
connection.connect();
connection.query('SELECT text, id from twits2 order by id ASC', function(err, rows) {
rows.forEach(function(row){
var id = row.id;
var r1 = sentiment(row.text);
var score = r1.score;
var comparative = r1.comparative;
var q = 'UPDATE twits2 SET score ="'+score+'", comparative ="'+comparative+'" WHERE id="'+id+'"';
console.log(q);
connection.query(q, function (error, results, fields) {
if (error) throw error;
});
});

How to obtain the value of the result in a `node-mysql` query

I am weighting a node.js application, the result I get from my mysql query is,
[ RowDataPacket { name: 'ubuntu' } ]
(Ubuntu is the only thing in the row)
What I would like to do is shorten my variable, "results" so that it equals ubuntu for example, or just every thing between the '', I am new to JS. I am using the standard way of querying the sql database,
It is being done as so:
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'root', //just using root for my personal testing.
password : 'root',
database : 'Sonic'
});
connection.connect();
var connect = connection.query( 'SELECT name FROM Sonic_url',
function(err, fields, results, rows) {
// if (results === input) {
var sqldata = results.substring(1, 4);
console.log(results);
if (err) throw err;
// console.log('I belive we have found what you are after, is: ' + input + ' ' + 'what you are after?');
//}
});
I would like to be able to do a basic IF with the variable input and a variable from the mysql query, so I can print to screen if the result was found or not.

The correct signature for the mysql query is:
connection.query(query, function (error, results, fields) {
// error will be an Error if one occurred during the query
// results will contain the results of the query
// fields will contain information about the returned results fields (if any)
});
What you want is to log the value of name. If your query produces one result, you can access this value from the first item in the rows array:
connection.query('SELECT name FROM Sonic_url', function(err, rows, fields) {
console.log(rows[0].name);
});