NodeJS with mysql returning the first query result

Question

I have a NodeJS with Express and mysql. I have put an Generic sql function so I call it for multiple times:

exports.selectCommand=function(table,cols,cond){
    var connection = mysql.createConnection({
        host     : hostname,
        database: databasename,
        user     : username
    });
    try{
        connection.query("SELECT "+cols+" As data from "+table+" where "+cond+" ", function(err, rows, fields) {
            if (err) return "sorry, an error accoured. Please try again later";
            if(rows.length!=0){
            cmd = rows[0].data.toString();
            }
        });
    }catch (e){console.log(e.message);}
    connection.end();
    return cmd; };

I send the query thorugh it but the problem it return the first query I send it.

I've put the above function in another file and I call it:

var db=require('./db.js');
..........
exports.psModel=function(){
    var cmddata="";
    cmddata=db.selectCommand("cmd","value","cmd='textbox'");
}

For some reason the var is not chainging it's value @amrswalha — amrswalha
– amrswalha, Commented Jul 8, 2013 at 13:56

luksch · Accepted Answer · 2013-07-08 13:42:51Z

2

your return cmd returns probably before the query is processed. The call is asynchronous. Try to place the return statement within the callback (and the connection end as well). Something like this:

try{
    connection.query("SELECT "+cols+" As data from "+table+" where "+cond+" ",
        function(err, rows, fields) {
            connection.end();
            if (err) return "sorry, an error occurred. Please try again later";
            if(rows.length!=0){
              cmd = rows[0].data.toString();
              return cmd;
            }
        });
    }catch (e){console.log(e.message);}

answered Jul 8, 2013 at 13:42

luksch

11.7k6 gold badges41 silver badges54 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

amrswalha Over a year ago

the cmd if it's inside the callback it return null value @luksch

luksch Over a year ago

can you log to the console how your SQL query looks like? also, log the result row to the console

amrswalha Over a year ago

SELECT value As data from cmd where cmd='textbox'

luksch Over a year ago

And what does the SELECT value As data from cmd where cmd='textbox'; return when you do it directly within the mysql console?

amrswalha Over a year ago

It return result but the value of the cmd does not change for some reason

|

Collectives™ on Stack Overflow

NodeJS with mysql returning the first query result

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related