Massive.DynamicModel.TryInvokeMember C# (CSharp) Method

        public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
        {
            //parse the method
            var constraints = new List<string>();
            var counter = 0;
            var info = binder.CallInfo;
            // accepting named args only... SKEET!
            if (info.ArgumentNames.Count != args.Length) {
                throw new InvalidOperationException("Please use named arguments for this type of query - the column name, orderby, columns, etc");
            }
            //first should be "FindBy, Last, Single, First"
            var op = binder.Name;
            var columns = " * ";
            string orderBy = string.Format(" ORDER BY {0}", PrimaryKeyField);
            string sql = "";
            string where = "";
            var whereArgs = new List<object>();

            //loop the named args - see if we have order, columns and constraints
            if (info.ArgumentNames.Count > 0) {
                for (int i = 0; i < args.Length; i++) {
                    var name = info.ArgumentNames[i].ToLower();
                    switch (name) {
                        case "orderby":
                            orderBy = " ORDER BY " + args[i];
                            break;
                        case "columns":
                            columns = args[i].ToString();
                            break;
                        default:
                            constraints.Add(string.Format(" {0} = @{1}", name, counter));
                            whereArgs.Add(args[i]);
                            counter++;
                            break;
                    }
                }
            }

            //Build the WHERE bits
            if (constraints.Count > 0) {
                where = " WHERE " + string.Join(" AND ", constraints.ToArray());
            }
            //probably a bit much here but... yeah this whole thing needs to be refactored...
            if (op.ToLower() == "count") {
                result = Scalar("SELECT COUNT(*) FROM " + TableName + where, whereArgs.ToArray());
            }
            else if (op.ToLower() == "sum") {
                result = Scalar("SELECT SUM(" + columns + ") FROM " + TableName + where, whereArgs.ToArray());
            }
            else if (op.ToLower() == "max") {
                result = Scalar("SELECT MAX(" + columns + ") FROM " + TableName + where, whereArgs.ToArray());
            }
            else if (op.ToLower() == "min") {
                result = Scalar("SELECT MIN(" + columns + ") FROM " + TableName + where, whereArgs.ToArray());
            }
            else if (op.ToLower() == "avg") {
                result = Scalar("SELECT AVG(" + columns + ") FROM " + TableName + where, whereArgs.ToArray());
            }
            else {
                //build the SQL
                sql = "SELECT TOP 1 " + columns + " FROM " + TableName + where;
                var justOne = op.StartsWith("First") || op.StartsWith("Last") || op.StartsWith("Get") || op.StartsWith("Single");

                //Be sure to sort by DESC on the PK (PK Sort is the default)
                if (op.StartsWith("Last")) {
                    orderBy = orderBy + " DESC ";
                }
                else {
                    //default to multiple
                    sql = "SELECT " + columns + " FROM " + TableName + where;
                }

                if (justOne) {
                    //return a single record
                    result = Query(sql + orderBy, whereArgs.ToArray()).FirstOrDefault();
                }
                else {
                    //return lots
                    result = Query(sql + orderBy, whereArgs.ToArray());
                }
            }
            return true;
        }