for(var i in cases) {
    var thequery = 'INSERT IGNORE INTO `cases` SET keysused='+cases.keysused+'
    pool.query(thequery, function(ee, rr) {
    if(ee) {
        logger.info(ee);
            throw ee;
    }
    });
}

var db_config = {
    connectionLimit : 5000,
    host: 'localhost',
    user: 'userexample'
    password: '*******',
    database: 'example.com'
};

function database_connection() {
pool = mysql.createPool(db_config);
pool.getConnection(function(err, connection) {
    if(err) {
        logger.error('[ERROR] Connecting to database "' + err.toString() + '"');
        setTimeout(function() { database_connection(); }, 2500);
    }
    else
    {
        pool.query('SET NAMES utf8');
        pool.query('SET CHARACTER SET utf8');
        logger.trace('[INFO] Connected to database and set utf8!');
    }
});