如何修复"源不包含任何数据行"？ [英] How to fix "The source contains no DataRows"?

问题描述

在这里，我想找到匹配的记录从两个数据表。代码

Here i want to find the Matched Records From Two data tables. the code is

public DataTable textfiltering(DataTable dtfff, DataTable dtff)
{
   DataTable ds = (DataTable)Session["maintxt"];
   DataTable dts = (DataTable)Session["sectxt"];
   dtfff = ds;
   dtff = dts;     

   DataTable dtMerged = (from a in dtfff.AsEnumerable()
                          join b in dtff.AsEnumerable()
                          on a["contacts"].ToString() equals b["contacts"].ToString()
                          into g                                 
                          where g.Count()>0                             
                          select a).CopyToDataTable();
           return dtMerged;    

}

它给源不包含任何数据行，当数据表不包含匹配的记录...
如何纠正it..pls给你suggistions

it gives "The source contains no DataRows" when Data tables does not contain Matched Records... How to rectify it..pls give your suggistions

推荐答案

有两种方式：

1. 要么检查它是否包含与行 Enumerable.Any 你打电话之前 CopyToDataTable


2. 使用 dtfff.Clone 以创建具有相同的架构作为一个空的DataTable源表，并使用一个循环从LINQ查询填充

1. either check if it contains rows with Enumerable.Any before you call CopyToDataTable
2. use dtfff.Clone to create an empty DataTable with the same schema as the source table and use a loop to fill it from the LINQ query.

第一种方法：

var rows = from a in dtfff.AsEnumerable()
           join b in dtff.AsEnumerable()
           on a["contacts"].ToString() equals b["contacts"].ToString()
           into g
           where g.Count() > 0
           select a;
DataTable merged;
if (rows.Any())
   merged = rows.CopyToDataTable();
else
    merged = dtfff.Clone();
return merged;

第二条本办法：

Second approach:

DataTable merged = dtfff.Clone();
foreach (DataRow sourceRow in rows)
{
   merged.ImportRow(sourceRow);  // or add all fields manually
}
return merged;

我更喜欢第二种方法，因为它只需要一次执行查询。

I prefer the second approach since it only needs to execute the query once.

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