BuildQuery

查询条件组合使用工具：

使用方法范例：

SqlConnection conn = new SqlConnection();
BuildQuery bq = new BuildQuery(conn);
bq.add("select * from products");
bq.byField("code", "A001"); //where code="A001";
bq.byBetween("num", 1,100); //where num between 1 and 100;
DataQuery ds = new bq.open();