Insert into two dependent tables in MySQL with node.js - mysql

Question

I am new to MySQL and node.js (as well as the callback). I try to insert data into table B, which depends on data in table A. Here is an example.
employee table (table A):
CREATE TABLE employees (
id int(11) NOT NULL AUTO_INCREMENT,
name varchar(50),
location varchar(50),
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=5 ;
age table (table B, I do not include age column in table A on purpose):
CREATE TABLE age (
id int(11) NOT NULL AUTO_INCREMENT,
index_id int(11),
age int(50),
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=5 ;
The problem:
For each row inserted into table A, I can get the id for it. I want to use the id as the index_id in table B, and insert the corresponding age info into age table B. The problem occurs when I have multiple rows to insert.
The example:
I implement the following function to achieve above goal.
var mysql = require("mysql");
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "root",
database: "sitepoint"
});
function insert_employees() {
var employees = [
{name: 'Jasmine', location: 'Australia', age: 24},
{name: 'Jay', location: 'India', age: 25},
{name: 'Jim', location: 'Germany', age: 26},
{name: 'Lesley', location: 'Scotland', age: 27}
];
var name_id;
for (var i = 0; i < 4; i++) {
var employee = employees[i];
var command = sprintf('INSERT INTO employees (name, location) VALUES ("%s", "%s");', employee.name, employee.location);
con.query(command, function (err, res) {
if (err) throw err;
name_id = res.insertId;
console.log('Last insert ID in employees:', res.insertID);
// insert age here
var age = employee.age;
var command = sprintf('INSERT INTO age (index_id, age) VALUES (%d, %d);', name_id, age);
con.query(command, function (err, res) {
if (err) throw err;
});
});
}
}
The Output:
The employee table is fine, but for the age table, the age column is 27 for all fields, instead of 24, 25, 26, 27
The Question:
I think the problem is on my misuse of callback feature, but I still don't know how to solve it. Could anyone help me with it? Thanks a lot!

Answer 1

var employee = employees[i];
Change the above line to below, so that variable employee has the correct scope:
let employee = employees[i];
Add the following to the beginning of your script, so that let works:
'use strict';