Node.js MYSQL to run each Queries sequencially after previous one is done?

Question

I'm using Javascript MYSQL Library from Node.js and then i have multiple queries to run in loop. But when i run the loop, the loop always reach to end (done) suddenly while the Queries it started are still processing. So how do i keep the loop to wait each Query til done and then continue normally?

My code is:

function startHere() {
    console.log("-- START --");
    for (i=1; i < 6; i++) {
        dbInsert(i);
    }
    console.log("-- END --");
}
function dbInsert(id) {
    connection.query (
        'INSERT INTO table SET data=?',
        [id],
        function selectCb(err, results, fields) {
            if (err) {
                console.log(err.message);
            }
            if (results.length > 0) {
                console.log(id+" RECORDS ADDED!");
            }
        }
    );
}
startHere();

When i run it, it always returns like:

-- START --
-- END --
1 RECORDS ADDED!
2 RECORDS ADDED!
3 RECORDS ADDED!
4 RECORDS ADDED!
5 RECORDS ADDED!

It means, the loop doesn't wait the end of the queries it started.
How can i detect the end-point of the queries and make it work?

I think this is a duplication to this: stackoverflow.com/questions/6638646/… — xiaoyi
– xiaoyi, Commented Jun 9, 2012 at 17:29
Firstly, get more familiar with what asynchronous stands for (Google is your friend on this one). Secondly, checkout this page. — Aleksei Zabrodskii
– Aleksei Zabrodskii, Commented Jun 10, 2012 at 2:16

Matthew Carriere · Accepted Answer · 2012-06-09 18:16:47Z

0

Your selectCb method is not being called synchronously, so your loop is effectively firing off each call and then returning.

You can either check the docs for a synchronous version of that connection.query method, or you will need to create a callback to print the end message after all your inserts have fired.

answered Jun 9, 2012 at 18:16

Matthew Carriere

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Comments

Jiew Meng · Accepted Answer · 2012-12-11 10:35:21Z

0

async should work for you

async.series([
    function(){ ... },
    function(){ ... }
]);

See https://github.com/caolan/async#series

answered Dec 11, 2012 at 10:35

Jiew Meng

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