linq to dataset 动态查询的一个问题

[dc22wt]

//这个表示选择第一个条件筛选出来的user_no
var query1 =
(from t in ds.Tables[0].AsEnumerable()
group t by t.Field<string>("user_no") into g
let fact_charge = g.Sum(p => p.Field<decimal>("fact_charge"))
where fact_charge > c
select new { user_no = g.Key }).Distinct();//Select(p=>p.Field<string>("user_no")
//这个表示选择第二个条件筛选出来的user_no
var query2 =
(from t in ds.Tables[0].AsEnumerable()
group t by t.Field<string>("user_no") into g
where g.Count() > d
select new { user_no = g.Key }).Distinct();
//这个表示选择第三个条件筛选出来的user_no
var query3 =
(from t in ds.Tables[0].AsEnumerable()
where Convert.ToInt32(t.Field<string>("gather_month")) <= b1
select new { p = t.Field<string>("user_no") }).Distinct();
客户可以随意选择这三个选项，求user_no得交集，最后将得到的user_no（暂定最后的结果为数据集query)再作为
var query4 =
from t in ds.Tables[0].AsEnumerable()
from o in query.AsEnumerable()
where o.user_no.ToString().Contains(t.Field<string>("user_no"))
orderby t.Field<string>("volpage"), t.Field<string>("user_no"), t.Field<string>("gather_month")
select t;
的查询子条件。急等各位大牛的援助。

[dc22wt]

怎么连个旁观的都没有啊，这么惨啊

[q107770540]

用 Intersect 方法求交集

最后查询可这样：

var query4 =
  from t in ds.Tables[0].AsEnumerable() 
  where query.Any(o=>o.user_no.ToString().Contains(t.Field<string>("user_no")))
  orderby t.Field<string>("volpage"), t.Field<string>("user_no"), t.Field<string>("gather_month")
  select t;

[q107770540]

使用了.Distinct() 还怎么可能延迟呢

[dc22wt]

这个我知道，就是因为现在用不了他的延迟特性，所以想请问下你能有其他办法帮我解决这个问题嘛

[dc22wt]

而且我即使把distinct去掉一样不会延迟查询

[dc22wt]

不行哦，我是要动态查询哦，现在我自己把代码修改了下，但是还有个问题就是每个子项的延迟查询的特性没有出来，造成的效率太低，希望你能帮我再看下

var query1 =
                            (from t in ds.Tables[0].AsEnumerable()
                             where Convert.ToInt32(t.Field<string>("gather_month")) <= b1
                             select new { user_no = t.Field<string>("user_no") }).Distinct();
                var query2 =
                           (from t in ds.Tables[0].AsEnumerable()
                            group t by t.Field<string>("user_no") into g
                            let fact_charge = g.Sum(p => p.Field<decimal>("fact_charge"))
                            where fact_charge > c
                            select new { user_no = g.Key }).Distinct();
           
                var query3 =
                            (from t in ds.Tables[0].AsEnumerable()
                            group t by t.Field<string>("user_no") into g
                            where g.Count() > d
                            select new { user_no = g.Key }).Distinct();
                var query4=
                            (from t in ds.Tables[0].AsEnumerable()
                             where t.Field<string>("volpage").Substring(0, 7)==f.ToString()
                             select new { user_no = t.Field<string>("user_no") }).Distinct();
                var refer =
                            from t in ds.Tables[0].AsEnumerable()
                            .Where(x => b >= 0 ? query1.AsEnumerable().Select(p => p.user_no).Contains (x.Field<string>("user_no")) : true)
                            .Where(x => c >= 0 && c != 1000000000 ? query2.AsEnumerable().Select(p => p.user_no).Contains(x.Field<string>("user_no")) : true)
                            .Where(x => d >= 0 && d != 1000000000 ? query3.AsEnumerable().Select(p => p.user_no).Contains(x.Field<string>("user_no")) : true)
                            .Where(x => f != "" ? query4.AsEnumerable().Select(p => p.user_no).Contains(x.Field<string>("user_no")) : true)
                            .Where(x => h =="1" ? x.Field<string>("DY_flag") == "1":true)
                            .OrderBy(o => o.Field<string>("volpage")).OrderBy(p=>p.Field<string>("user_no")).OrderBy(q=>q.Field<string>("gather_month"))
                            select t;
                   
                
                if (refer.Count() == 0)     //判断refer的记录是否为0
                {
                    CreateColumnFooter();
                    CreateGroupFooter(1);
                    MessageBox.Show("没有符合此条件的选项，请重新输入", "信息提示", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Warning);
                }
                else
                {
                   
                    DataView filter = refer.AsDataView();
                    this.fpSpread1_Sheet1.DataSource = filter;}

[dc22wt]

还有谁能帮我看看嘛

[dc22wt]

不好意思，我没看懂你的意识，我不知道你这个能不能实现动态查询，如果可以的话，还烦请你能否讲详细点，或者需要参考什么知识，请帮忙说下

[FelixFJ]

像这样多条件查询的，一个where是搞不定的，我给个例子你参考一下：

private bool FiltVisitor(VisitingInfo v, string visitorName, string visitorCorp, string revEmpName,
             string fromVisitTime, string toVisitTime, string token)
        {
            bool ret = true;            
            if (!string.IsNullOrEmpty(visitorName))
                ret &= v.VisitorName.Contains(visitorName);
            if (!string.IsNullOrEmpty(visitorCorp))
                ret &= v.VisitorCorp.Contains(visitorCorp);
            if (!string.IsNullOrEmpty(revEmpName))
                ret &= v.RevEmpName.Contains(revEmpName);
            if (!string.IsNullOrEmpty(fromVisitTime))
                ret &= v.VisitorComeTime >= Convert.ToDateTime(fromVisitTime);
            if (!string.IsNullOrEmpty(toVisitTime))
                ret &= v.VisitorComeTime <= Convert.ToDateTime(toVisitTime);
            return ret;

        }   

                System.Linq.Expressions.Expression<Func<VisitingInfo, bool>> exp = v =>
                    FiltVisitor(v, visitorName, visitorCorp, revEmpName, fromVisitTime, toVisitTime, token);

                result.Data = this.GetVisitingInfo(fromVisitTime, toVisitTime).VisitingInfos.AsEnumerable().Where(exp.Compile());

[FelixFJ]

就是先根据业务需求，写要要过滤的条件函数 ，然后使用System.Linq.Expressions.Expression<Func<VisitingInfo, bool>> exp = v =>你的函数
最后在where(你的函数())

[dc22wt]

不明白。。。

[狂奔小蜗牛]

[Quote=引用 2 楼 q107770540 的回复:]
用 Intersect 方法求交集

最后查询可这样：

C# code


var query4 =
from t in ds.Tables[0].AsEnumerable()
where query.Any(o=>o.user_no.ToString().Contains(t.Field<string>("user_no")))
orderby t.Field……
[/Quote]

O(∩_∩)O~