Allow empty array or value of `order`

lib/sql.js

@@ -1216,6 +1216,9 @@ SQLConnector.prototype.buildOrderBy = function(model, order) {
       clauses.push(self.columnEscaped(model, t[0]) + ' ' + t[1]);
     }
   }
+  if (!clauses.length) {
+    return '';
+  }
   return 'ORDER BY ' + clauses.join(',');
 };
 

test/sql.test.js

@@ -270,6 +270,16 @@ describe('sql connector', function() {
     expect(orderBy).to.eql('ORDER BY `NAME` ASC,`VIP` DESC');
   });
 
+  it('builds order by with empty array', function() {
+    const orderBy = connector.buildOrderBy('customer', []);
+    expect(orderBy).to.eql('');
+  });
+
+  it('builds order by with empty string', function() {
+    const orderBy = connector.buildOrderBy('customer', '');
+    expect(orderBy).to.eql('');
+  });
+
   it('builds fields for columns', function() {
     const fields = connector.buildFields('customer',
       {name: 'John', vip: true, unknown: 'Random'});