Add string overloads for Sql.Aggregate operators so they can be used as-is in Select expressions

Author: mythz

src/ServiceStack.OrmLite/Expressions/Sql.cs

@@ -1,20 +1,20 @@
 using System.Collections;
 using System.Linq;
-using System.Collections.Generic;
-
-namespace ServiceStack.OrmLite
-{
-	public static class Sql
-	{
+using System.Collections.Generic;
+
+namespace ServiceStack.OrmLite
+{
+    public static class Sql
+    {
         public static bool In<T, TItem>(T value, params TItem[] list)
         {
             return value != null && Flatten(list).Any(obj => obj.ToString() == value.ToString());
         }
 
-	    public static List<object> Flatten(IEnumerable list)
+        public static List<object> Flatten(IEnumerable list)
         {
             var ret = new List<object>();
-	        if (list == null) return ret;
+            if (list == null) return ret;
 
             foreach (var item in list)
             {
@@ -33,35 +33,66 @@ public static List<object> Flatten(IEnumerable list)
             return ret;
         }
 
-	    public static string Desc<T>(T value)
-        {
-			return  value==null? "": value.ToString() + " DESC";
-		}
-		
-		public static string As<T>( T value, object asValue) {
-			return  value==null? "": string.Format("{0} AS {1}", value.ToString(), asValue);
-		}
-		
-		public static T Sum<T>( T value)  {
-			return value;
-		}
-		
-		public static T Count<T>( T value)  {
-			return value;
-		}
-		
-		public static T Min<T>( T value)  {
-			return value;
-		}
-		
-		public static T Max<T>( T value)  {
-			return value;
-		}
-		
-		public static T Avg<T>( T value)  {
-			return value;
-		}
-	}
-		
-}
-
+        public static string Desc<T>(T value)
+        {
+            return value == null ? "" : value.ToString() + " DESC";
+        }
+
+        public static string As<T>(T value, object asValue)
+        {
+            return value == null ? "" : string.Format("{0} AS {1}", value.ToString(), asValue);
+        }
+
+        public static T Sum<T>(T value)
+        {
+            return value;
+        }
+
+        public static string Sum(string value)
+        {
+            return "SUM({0})".Fmt(value);
+        }
+
+        public static T Count<T>(T value)
+        {
+            return value;
+        }
+
+        public static string Count(string value)
+        {
+            return "COUNT({0})".Fmt(value);
+        }
+
+        public static T Min<T>(T value)
+        {
+            return value;
+        }
+
+        public static string Min(string value)
+        {
+            return "MIN({0})".Fmt(value);
+        }
+
+        public static T Max<T>(T value)
+        {
+            return value;
+        }
+
+        public static string Max(string value)
+        {
+            return "MAX({0})".Fmt(value);
+        }
+
+        public static T Avg<T>(T value)
+        {
+            return value;
+        }
+
+        public static string Avg(string value)
+        {
+            return "AVG({0})".Fmt(value);
+        }
+    }
+
+}
+