How do I use var into query request in javascript?

Question

Hello i'm struggling with using variables that I declared into my jquery request:

var int_example = "42";
int_example = parseInt(id);
var string_example = "42";

const { Client } = require('pg')
const client = new Client({
    user: 'postgres',
    host: 'localhost',
    database: 'postgres',
    password: 'password',
    port: 5432
});

var query = "INSERT INTO data (int,string) VALUES (int_example,string_example);
client.connect()
    .then(() => console.log("Connection a la base de données réussie"))
    .then(() => console.log("Nos commandes:"))
    .catch(e => console.log(e))
    .then(() => client.query(query))

I get this kind of error : "{ error: column "int_example" does not exist" and i'm not sure if the string_example works as well... Seems I can't use type var or i'm doing something wrong please tell me.

Thank you

Mohammad Salehi · Accepted Answer · 2022-04-14 22:05:18Z

1

there are two ways to put variables in JS strings:

concatenation

var query = "INSERT INTO data (int,string) VALUES (" + int_example + ",'" + string_example + "');";

using template literals (recommended)

var query = `INSERT INTO data (int,string) VALUES (${int_example},'${string_example}');`

right now your query does not contain values of int_example and string_example and it's just their names.

answered Apr 14, 2022 at 22:05

Mohammad Salehi

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6 Comments

GGH Over a year ago

i get { error: syntax error at or near "$" with using template literals

Mohammad Salehi Over a year ago

make sure you put backticks (`) correctly.

GGH Over a year ago

Oh! Thank you seems that ' is not same as ` that's why it didn't work, but now I have { error: duplicate key value violates unique constraint "commande_pkey" do you have any idea ?

Mohammad Salehi Over a year ago

link check this.

GGH Over a year ago

I think it's because i'm trying to INSERT INTO data (int_data) VALUES (${int_example}) but my int_data is a primarey key

|

mohammedabdulai · Accepted Answer · 2022-04-14 22:10:55Z

0

Your issues results from your query string. The values of int_example and string_example are not present in your query.

You can fix the issue by either using string interpolation or string concatenation

You solution will be to use one of the below options:

String Interpolation:

var query = `INSERT INTO data (int,string) VALUES (${int_example},${string_example})`;

String Concatenation:

var query = "INSERT INTO data (int,string) VALUES (" + int_example + "," + string_example + ")";

Note: Whenever you create a string from a string and a number/int the result is a string. Number/int is converted into a string when concatenating.

answered Apr 14, 2022 at 22:10

mohammedabdulai

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1 Comment

GGH Over a year ago

i get { error: syntax error at or near "$" with String interpolation

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