Node.js mysql query is undefined

Question

I'm running the following code on Node.js and I am trying to use mysql with nodejs : trying to run the query: select numbers from TABLE . The result comes out as:

"undefined"

function getNumbers()
{
    cio.query("SELECT numbers FROM rooms WHERE durum='1'", function(err, result)
    {
        if (err) 
         throw err;
        else
     result[0].numbers;

    });

}
var kar = getNumbers();
 console.log(kar);

So, what should I do ? Please help.

Answer 1

Functions getNumbers() and the function called inside it don't return any values, so the result will always be undefined .

Other than that you need to handle the asynchronous nature of the function:
wait until the database query is complete before returning a value .
You can do this by using a callback function .

Example below:

function getNumbers(callback) {
    cio.query("SELECT numbers FROM rooms WHERE durum='1'", function (err, result) {
        if (err) throw err;
        callback((result.length > 0) ? result[0].numbers : "");
    });
}

getNumbers(function (result) {
    console.log(result);
});

Answer 2

I don't know if your question depends on your console.log but your function has no return value. So when you have no return then it's undefined .

function getNumbers() {
    return 'test';
}
var kar = getNumbers();
console.log(kar);