Add OrderByDescending to IUntypedSqlExpression

Author: mythz

src/ServiceStack.OrmLite/Expressions/IUntypedSqlExpression.cs

@@ -65,6 +65,7 @@ public interface IUntypedSqlExpression : ISqlExpression
         IUntypedSqlExpression ThenBy(string orderBy);
         IUntypedSqlExpression ThenBy<Table>(Expression<Func<Table, object>> keySelector);
         IUntypedSqlExpression OrderByDescending<Table>(Expression<Func<Table, object>> keySelector);
+        IUntypedSqlExpression OrderByDescending(string orderBy);
         IUntypedSqlExpression ThenByDescending(string orderBy);
         IUntypedSqlExpression ThenByDescending<Table>(Expression<Func<Table, object>> keySelector);
 
@@ -416,6 +417,12 @@ public IUntypedSqlExpression OrderByDescending<Table>(Expression<Func<Table, obj
             return this;
         }
 
+        public IUntypedSqlExpression OrderByDescending(string orderBy)
+        {
+            q.OrderByDescending(orderBy);
+            return this;
+        }
+
         public IUntypedSqlExpression ThenByDescending(string orderBy)
         {
             q.ThenByDescending(orderBy);