DataTableReader.GetDataTypeName(Int32) 方法

定义

命名空间:

System.Data

程序集:

System.Data.Common.dll

Source:

DataTableReader.cs

获取一个表示指定列的数据类型的字符串。

public:
 override System::String ^ GetDataTypeName(int ordinal);

public override string GetDataTypeName (int ordinal);

override this.GetDataTypeName : int -> string

Public Overrides Function GetDataTypeName (ordinal As Integer) As String

参数

ordinal

Int32

从零开始的列序号。

返回

String

一个表示列的数据类型的字符串。

例外

ArgumentOutOfRangeException

传递的索引超出了 0 到 FieldCount -1 的范围。

InvalidOperationException

尝试读取或访问已关闭的 DataTableReader 中的列。

示例

以下控制台应用程序显示来自简单 DataTable的字段及其类型名称的列表：

private static void TestGetTypeName()
{
    DataTable table = GetCustomers();
    using (DataTableReader reader = new DataTableReader(table))
    {
        for (int i = 0; i < reader.FieldCount; i++)
        {
            Console.WriteLine("{0}: {1}", reader.GetName(i),
                reader.GetDataTypeName(i));
        }
    }
    Console.WriteLine("Press Enter to finish.");
    Console.ReadLine();
}

private static DataTable GetCustomers()
{
    // Create sample Customers table, in order
    // to demonstrate the behavior of the DataTableReader.
    DataTable table = new DataTable();
    // Create two columns, ID and Name.
    DataColumn idColumn = table.Columns.Add("ID", typeof(int));
    table.Columns.Add("Name", typeof(string ));
    // Set the ID column as the primary key column.
    table.PrimaryKey = new DataColumn[] { idColumn };

    table.Rows.Add(new object[] { 1, "Mary" });
    table.Rows.Add(new object[] { 2, "Andy" });
    table.Rows.Add(new object[] { 3, "Peter" });
    table.Rows.Add(new object[] { 4, "Russ" });
    return table;
}

Private Sub TestGetTypeName()
   Dim table As DataTable = GetCustomers()
   Using reader As New DataTableReader(table)
      For i As Integer = 0 To reader.FieldCount - 1
         Console.WriteLine("{0}: {1}", _
            reader.GetName(i), reader.GetDataTypeName(i))
      Next
   End Using

   Console.WriteLine("Press Enter to finish.")
   Console.ReadLine()
End Sub

Private Function GetCustomers() As DataTable
   ' Create sample Customers table, in order
   ' to demonstrate the behavior of the DataTableReader.
   Dim table As New DataTable

   ' Create two columns, ID and Name.
   Dim idColumn As DataColumn = table.Columns.Add("ID", _
     GetType(Integer))
   table.Columns.Add("Name", GetType(String))

   ' Set the ID column as the primary key column.
   table.PrimaryKey = New DataColumn() {idColumn}

   table.Rows.Add(New Object() {1, "Mary"})
   table.Rows.Add(New Object() {2, "Andy"})
   table.Rows.Add(New Object() {3, "Peter"})
   table.Rows.Add(New Object() {4, "Russ"})
   Return table
End Function

控制台窗口显示以下结果：

ID: Int32  
Name: String  

注解

方法 GetDataTypeName 始终返回基础 DataColumn 的类型，而不是特定于提供程序的类型。