Question

这有效：

using System;
using System.Collections.Generic;
using System.Data;     
using System.Data.Common;
using System.Data.OleDb;

public class MyClass
{
    public static void Main()
    {
    OleDbConnection mySqlConnection =new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\data\nwind.Mdb");

    OleDbCommand mySqlCommand = mySqlConnection.CreateCommand();
    mySqlCommand.CommandText = "SELECT EmployeeID AS MappedID, FirstName, LastName " +
      "FROM Employees AS Emp " +
      "WHERE EmployeeID = 9";
    OleDbDataAdapter mySqlDataAdapter = new OleDbDataAdapter();
    mySqlDataAdapter.SelectCommand = mySqlCommand;
    DataSet myDataSet = new DataSet();
    mySqlConnection.Open();
    mySqlDataAdapter.Fill(myDataSet, "Employees");
    mySqlConnection.Close();

    DataTableMapping myDataTableMapping = mySqlDataAdapter.TableMappings.Add("Employees", "dtEmployee");

    myDataSet.Tables["Employees"].TableName = "dtEmployee";

    Console.WriteLine("myDataTableMapping.DataSetTable = " + myDataTableMapping.DataSetTable);
    Console.WriteLine("myDataTableMapping.SourceTable = " + myDataTableMapping.SourceTable);

    myDataTableMapping.ColumnMappings.Add("EmployeeID", "MappedId");

    DataTable myDataTable = myDataSet.Tables["dtEmployee"];
    foreach (DataRow myDataRow in myDataTable.Rows)
    {
      Console.WriteLine("ID = " + myDataRow["MappedId"]);
      Console.WriteLine("FirstName = " + myDataRow["FirstName"]);
      Console.WriteLine("LastName = " + myDataRow["LastName"]);
    }   
        Console.ReadLine();
    }

}

只需将“MappedId”更改为“NewMappedId”：

myDataTableMapping.ColumnMappings.Add("EmployeeID", "NewMappedId");
Console.WriteLine("ID = " + myDataRow["NewMappedId"]);

到“NewMappedId”之类的其他内容，程序将在运行时崩溃，说NewMappedId不属于表dtEmployee。这是一个错误吗？！

Answer 1

这里没有错误。

如果更改绑定数据集的内容，则此错误是正常的，因为您不再匹配绑定的基础架构。

.NET ColumnMappings类中是否有错误？

1 个答案: