- 增加 ISelect ToDelete/ToUpdate 方法，实现更复杂的删除/更新操作；

Providers/FreeSql.Provider.SqlServer/SqlServerUtils.cs

@@ -62,7 +62,11 @@ namespace FreeSql.SqlServer
             var sb = new StringBuilder();
             var news = new string[objs.Length];
             for (var a = 0; a < objs.Length; a++)
-                news[a] = types[a] == typeof(string) ? objs[a] : $"cast({objs[a]} as nvarchar)";
+            {
+                if (types[a] == typeof(string)) news[a] = objs[a];
+                else if (types[a].NullableTypeOrThis() == typeof(Guid)) news[a] = $"cast({objs[a]} as char(36))";
+                else news[a] = $"cast({objs[a]} as nvarchar)";
+            }
             return string.Join(" + ", news);
         }
         public override string Mod(string left, string right, Type leftType, Type rightType) => $"{left} % {right}";