如何在多個條件列上連接兩個數據表？

Question

我有兩個數據表，我想和他們一起幾個columns.here是我的代碼

 DataTable targetTable = dtl.Clone(); 
     var dt2Columns = dt.Columns.OfType<DataColumn>().Select(dc => 
      new DataColumn(dc.ColumnName, dc.DataType, dc.Expression, dc.ColumnMapping)); 
     targetTable.Columns.AddRange(dt2Columns.ToArray()); 
     var rowData = 
      from row1 in dtl.AsEnumerable() 
      join row2 in dt.AsEnumerable()     
       on row1.Field<string>("header") 
      equals row2.Field<string>("header") 
      where (row1.Field<string>("digitnumber") != "") 
      select row1.ItemArray.Concat(row2.ItemArray).ToArray(); 
     foreach (object[] values in rowData) 
      targetTable.Rows.Add(values); 

，但它的連接只在一個condition.I要像下面的代碼：

DataTable targetTable = dtl.Clone(); 
     var dt2Columns = dt.Columns.OfType<DataColumn>().Select(dc => 
      new DataColumn(dc.ColumnName, dc.DataType, dc.Expression, dc.ColumnMapping)); 
     targetTable.Columns.AddRange(dt2Columns.ToArray()); 
     var rowData = 
      from row1 in dtl.AsEnumerable() 
      join row2 in dt.AsEnumerable()     
       on row1.Field<string>("header") and row1.Field<string>("digitrow") and row1.Field<string> ("response") 
      equals row2.Field<string>("header") and row1.Field<string>("question") and and row1.Field<string> ("answer") 
      where (row1.Field<string>("digitnumber") != "") 
      select row1.ItemArray.Concat(row2.ItemArray).ToArray(); 
     foreach (object[] values in rowData) 
      targetTable.Rows.Add(values); 

但在多種情況下有一些錯誤。解決方法是什麼？請幫助我。

Answer 1

from table1 in dt.TableA 
join table2 in dt.Table2 on 
      new { table1.col1, table1.col2} 
      equals 
      new { table2.Column1,table2.Column2} 

您可以在相同的順序中添加多列以供比較。