c# - DataTable Linq 连接多列

Question

我在使用 Linq Join 时遇到了问题。我想加入 2 个表，它们与 n 列具有相同的结构。我的问题是我不知道这些列的名称，所以如何在 select new 中重写它们？

表 1:这里我在 ID、Name 和 LastName 中有一些参数。 Comment, Attribute 其余为空

 ID    Name   LastName  Comment   Attribute ...     
                         "what"   "ABC"     ...
                         "hello"  "SDE"     ...
 3     lola               
 1              de           
 4     miki      
 ...   ...      ...      ...  

表2:与表1相同，但在Comment、Attribute和Rest中有一些参数。

 ID    Name   LastName  Comment   Attribute ...
                        "what"   "ABC"     ...
                        "hello"  "SDE"     ...
 1              de       "hi"     
 4     miki                      "OKK"
 3     lola             "yo"     "LL"

结果:我想加入这样的表

 ID    Name   LastName  Comment   Attribute ...
                        "what"   "ABC"     ...
                        "hello"  "SDE"     ...
 3     lola               "yo"    "LL" 
 1               de        "hi"   
 4     miki                       "OKK"
 ...   ...      ...      ...       ...     ...

我的代码是:

var Result= from tb1 in table1.AsEnumerable()
            join tb2 in tabl2.AsEnumerable()
            on new
            {                
             Name = tb1.Field<String>("Name"),
             LastName = tb1.Field<String>("LastName"),
             } equals new
            {
             Name=tb2.Field<String>("Name"),
             LastName=tb2.Field<String>("LastName"),
             }
            into grp1
            from tb3 in grp1.DefaultIfEmpty()
            select new
    {
     ID = tb1.Field<String>("ID"),
     Name = tb1.Field<String>("Name") ,
     LastName = tb1.Field<String>("LastName"),
     Comment = tb3!= null ? tb3.Field<String>("Comment") : null,
     Attribute= tb3!= null ? tb3.Field<String>("Attribute") : null,
     ...
     // Here should be next Columns Name but don't know how to put there

     };

---

我试过这段代码，但我的编译器挂掉了，不知道为什么

        for (int i = 2; i < table1.Rows.Count; i++)
        {
            foreach (DataRow dr in table2.Rows)
            {
                if ((table1.Rows[i]["Name"].ToString() == dr["Name"].ToString())&&table1.Rows[i]["LastName"].ToString() == dr["LastName"].ToString())
                {
                    table1.Rows.RemoveAt(i);
                    table1.ImportRow(dr);

                }
            }
        }
        dataGridView1.DataSource = table1;

Answer 1

对于table1中的每个row1，如果table2中有匹配的row2，则使用row2。否则，使用第 1 行。

var newTable = table1.Clone();
foreach (DataRow row1 in table1.Rows) // To skip the first 2, use table1.Rows.Cast<DataRow>().Skip(2)
{
    var row = table2.Rows.Cast<DataRow>().FirstOrDefault(row2 => 
                row1["Name"].ToString() == row2["Name"].ToString() &&
                row1["LastName"].ToString() == row2["LastName"].ToString()) ?? row1;
    newTable.ImportRow(row);
}
dataGridView1.DataSource = newTable;