node.js function returning 'undefined' from mysql query

Question

My function 'getWebshopByID' is returning 'undefined' but if I write the code outside the function it works fine... What am I doing wrong?

con.connect(function(err) {
if (err) throw err;
var sql = "SELECT `ID` FROM `tms_posts` WHERE `post_type`= 'nf_sub' AND `post_status` != 'Trash'";
con.query(sql, function (err, result, fields) {
    if (err) throw err;
    //sql = "SELECT `meta_value` FROM `tms_postmeta` WHERE `post_id` = ? AND `meta_key` = '_field_5'";
    Object.keys(result).forEach(function(key) {
        var webshop = getWebshopByID(result[0].ID);
        console.log(webshop);
    })
})

})

function getWebshopByID(ID) {
var myvalue;
var sql = "SELECT `meta_value` FROM `tms_postmeta` WHERE `post_id` = ? AND `meta_key` = '_field_5'";
con.query(sql, ID, function (err, result, fields) {
    if (err) throw err;
    myvalue = result[0].meta_value;
})
return myvalue;

}