Result for Node.js MySQL query

Question

I want to know if node.js mysql gives a query success indicator. I want to do a CREATE DATABASE IF NOT EXIST query, and if the database did not exist and was created properly, execute a bunch of files (that create my tables). The files that create the tables are already coded and I tested them. I just do not understand (due to really meh documentaton) how to do "if database was successfully created do x else do y" portion of the logic.

const config = require("./database");

var connection = config.db.get;

connection.query(
    "CREATE DATABASE IF NOT EXISTS " . config.database,
    function (err, result, fields) {
        if (err) throw err;

        console.log("result: " + result);

        if(!success) {
            //do nothing, we assume the database adn tables are already setup.
        }
        else {
            require("./models/company");
            require("./models/locations");
        }
    });

How can I create a boolean variable based on if the query was successful or not, assuming that it would be false if the database exists before running the CREATE DATABASE query.

11AND2 · Accepted Answer · 2018-06-05 08:29:54Z

1

Your "IF NOT EXISTS" part suppresses the "error". So you could either:

Just do a "CREATE DATABASE ABC" - this should throw an error. So you could do if (err) {...do something...}
You could check beforehand if the database exists with something like this "SELECT SCHEMA_NAME FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = 'ABC'"

answered Jun 5, 2018 at 8:29

11AND2

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4 Comments

Joshua Blevins Over a year ago

I will try this when I get home from work. Is the error a blank string if the query is successful?

11AND2 Over a year ago

I don't know for mysql. Usually it's null so "if (err === null) {...all good...}"

Joshua Blevins Over a year ago

Ill try both and start to document how the module works on my website.

Joshua Blevins Over a year ago

It is correct to say that if err is not null, the query did not return results.

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