public override string ToStr()
        {
            StringBuilder sb = new StringBuilder();

            sb.Append("update ").Append(TableClause.ToStr());
            if (Set.Count > 0)
            {
                sb.Append(" SET ");
                for (int i = 0; i < Set.Count; i++)
                {
                    var sc = Set[i];
                    if (i > 0)
                    {
                        sb.Append(", ");
                    }
                    sb.Append(sc.ToStr());
                }
            }
            if (Where != null)
            {
                sb.Append(" where ").Append(Where.ToStr());
            }
            AddReturningToStr(sb);
            return(sb.ToString());
        }
        public override string ToStr()
        {
            StringBuilder sb = new StringBuilder();

            sb.Append("delete from ").Append(TableClause.ToStr());
            if (Where != null)
            {
                sb.Append(" where ").Append(Where.ToStr());
            }
            AddReturningToStr(sb);
            return(sb.ToString());
        }
        public override string ToStr()
        {
            StringBuilder sb = new StringBuilder();

            sb.Append("insert into ").Append(TableClause.ToStr());
            if (DefaultValues)
            {
                sb.Append(" DEFAULT VALUES");
            }
            else
            {
                if (ColumnOfValues.Count > 0)
                {
                    sb.Append(" ( ");
                    for (int i = 0; i < ColumnOfValues.Count; i++)
                    {
                        var sc = ColumnOfValues[i];
                        if (i > 0)
                        {
                            sb.Append(", ");
                        }
                        sb.Append(sc.ToStr());
                    }
                    sb.Append(")");
                }
                if (Values != null && Values.Count > 0)
                {
                    sb.Append(" values");
                    for (int i = 0; i < Values.Count; i++)
                    {
                        var sc = Values[i];
                        //sb.Append("(");
                        if (i > 0)
                        {
                            sb.Append(", ");
                        }
                        sb.Append(sc.ToStr());
                        //sb.Append(")");
                    }
                }
                else
                {
                    sb.Append(" ").Append(Select.ToStr());
                }
            }
            AddReturningToStr(sb);
            return(sb.ToString());
        }