diff --git a/lib/mysql.js b/lib/mysql.js
index 0e5334e..f812703 100644
--- a/lib/mysql.js
+++ b/lib/mysql.js
@@ -135,7 +135,9 @@ MySQL.prototype.toFields = function (model, data) {
     var props = this._models[model].properties;
     Object.keys(data).forEach(function (key) {
         if (props[key]) {
-            fields.push('`' + key.replace(/\./g, '`.`') + '` = ' + this.toDatabase(props[key], data[key]));
+            var value = this.toDatabase(props[key], data[key]);
+            if ('undefined' === typeof value) return;
+            fields.push('`' + key.replace(/\./g, '`.`') + '` = ' + value);
         }
     }.bind(this));
     return fields.join(',');
@@ -156,6 +158,7 @@ function dateToMysql(val) {
 
 MySQL.prototype.toDatabase = function (prop, val) {
     if (val === null) return 'NULL';
+    if (val === undefined) return;
     if (val.constructor.name === 'Object') {
         var operator = Object.keys(val)[0]
         val = val[operator];
@@ -299,7 +302,11 @@ MySQL.prototype.all = function all(model, filter, callback) {
 
     function buildOrderBy(order) {
         if (typeof order === 'string') order = [order];
-        return 'ORDER BY ' + order.join(', ');
+        return 'ORDER BY ' + order.map(function(o) {
+            var t = o.split(/\s+/);
+            if (t.length === 1) return '`' + o + '`';
+            return '`' + t[0] + '` ' + t[1];
+        }).join(', ');
     }
 
     function buildLimit(limit, offset) {