linq中group by后如何对其他列count

[friwhibo]

 var reportQuery = from a in examReportTable.AsEnumerable()
                   join b in rvuTable.AsEnumerable()
                   on new { exam = a.Field<string>("exam"), examtype = a.Field<string>("examtype") } equals new { exam = b.Field<string>("rvuName"), examtype = b.Field<string>("rvuType") }
                   group b by new { reportDoc = a.Field<string>("reportDoc"), examtype = a.Field<string>("examtype") } into c
                   select new
                   {
                       DocName = c.Key.reportDoc,
                       examType = c.Key.examtype,
                       reportDocRvu = c.Sum(o => double.Parse(o.Field<string>("reportRvu"))),
                       reportDocNum =//examReportTable中对“exam”计数count这句怎么写？
                    };

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版主提醒： 下次提问时，请将你的代码格式化一下

[friwhibo]

还有字符串转换为double有没有其他方法，我的转换结果中会出现：3.99999999999之类的情况，实际上最多小数点后1位

[EnForGrass]

var reportQuery = from a in examReportTable.AsEnumerable() join b in rvuTable.AsEnumerable() on new { exam = a.Field<string>("exam"), examtype = a.Field<string>("examtype") } equals new { exam = b.Field<string>("rvuName"), examtype = b.Field<string>("rvuType") } group b by new { reportDoc = a.Field<string>("reportDoc"), examtype = a.Field<string>("examtype") } into c select new { DocName = c.Key.reportDoc, examType = c.Key.examtype, reportDocRvu = c.Sum(o => double.Parse(o.Field<string>("reportRvu"))), reportDocNum = c.Count(d=>d.Field<string>("exam")) }; 为什么reportRvu不定义成decimal类型呢，或者你试试Convert.ToDecimal()

[friwhibo]

报错 错误 1 无法将 lambda 表达式 转换为委托类型“System.Func<System.Data.DataRow,bool>”，原因是块中的某些返回类型不能隐式转换为委托返回类型 错误 2 无法将类型“string”隐式转换为“bool”

[friwhibo]

Convert.ToDecimal()确实解决了小数点的问题，谢谢，但count依然无法通过编译

[q107770540]

给出你两个DataTable的定义结构和测试数据

[q107770540]

var reportQuery = from a in examReportTable.AsEnumerable()
                   join b in rvuTable.AsEnumerable()
                   on new { exam = a.Field<string>("exam"), examtype = a.Field<string>("examtype") } equals new { exam = b.Field<string>("rvuName"), examtype = b.Field<string>("rvuType") }
                   group new {a,b} by new { reportDoc = a.Field<string>("reportDoc"), examtype = a.Field<string>("examtype") } into c
                   select new
                   {
                       DocName = c.Key.reportDoc,
                       examType = c.Key.examtype,
                       reportDocRvu = c.Sum(o => Convert.ToDecimal(o.Field<string>("reportRvu"))),
                       reportDocNum =c.Count(x=>x.Field<string>("exam"))
                    };

[friwhibo]

无法将 lambda 表达式 转换为委托类型“System.Func<System.Data.DataRow,bool>”，原因是块中的某些返回类型不能隐式转换为委托返回类型 无法将类型“string”隐式转换为“bool”

[friwhibo]

这两个表是分别从两个数据库读出来的，没有专门去定义什么：这两个
数据库都是从单位导出样本acsess数据库，再导入到自己sql的，都是ntext的，允许null。

            LinkDataBase rvuLink = new LinkDataBase();
            rvuDs = rvuLink.SelectDataBase(rvuSendStrSQL, rvuSendTableName, rvuSendConnectionString);
            rvuTable = rvuDs.Tables[0];
            LinkDataBase examLink1 = new LinkDataBase();
            examReportDs = examLink1.SelectDataBase(examReportSendStrSQL, examSendTableName1, examSendConnectionString);
            examReportTable = examReportDs.Tables[0];

样本数据是这样子的
因为select 用了as 所以代码里的列表有所不同

[friwhibo]

这个count是要计算，每个医生CT做了多少个，MR做了多少个。。。。

[friwhibo]

终于解决了,但是方法很搞笑!!!

var reportQuery = from a in examReportTable.AsEnumerable()
                   join b in rvuTable.AsEnumerable()
                   on new { exam = a.Field<string>("exam"), examtype = a.Field<string>("examtype") } equals new { exam = b.Field<string>("rvuName"), examtype = b.Field<string>("rvuType") }
                   group new {a,b} by new { reportDoc = a.Field<string>("reportDoc"), examtype = a.Field<string>("examtype") } into c
                   select new
                   {
                       DocName = c.Key.reportDoc,
                       examType = c.Key.examtype,
                       reportDocRvu = c.Sum(o => Convert.ToDecimal(o.Field<string>("reportRvu"))),
                       reportDocNum =c.Count(x=>x.Field<string>("exam")==x.Field<string>("exam"))
                    };