DataTableReader.HasRows Properti

Definisi

Ruang nama:

System.Data

Rakitan:

System.Data.Common.dll

Sumber:

DataTableReader.cs

Mendapatkan nilai yang menunjukkan apakah DataTableReader berisi satu atau beberapa baris.

public:
 virtual property bool HasRows { bool get(); };

public override bool HasRows { get; }

member this.HasRows : bool

Public Overrides ReadOnly Property HasRows As Boolean

Nilai Properti

Boolean

trueDataTableReader jika berisi satu atau beberapa baris; jika tidak false.

Pengecualian

InvalidOperationException

Upaya dilakukan untuk mengambil informasi tentang tertutup DataTableReader.

Contoh

Contoh berikut mengisi dua DataTable instans dengan data. Yang pertama DataTable berisi satu baris, dan baris kedua tidak berisi baris. Contoh kemudian membuat DataTableReader yang berisi kedua DataTable objek, dan memanggil metode PrintData untuk menampilkan konten masing-masing, memeriksa nilai HasRows properti masing-masing sebelum melakukan panggilan ke PrintData.

private static void TestHasRows()
{
    DataTable customerTable = GetCustomers();
    DataTable productTable = GetProducts();

    using (DataTableReader reader = new DataTableReader(
               new DataTable[] { customerTable, productTable }))
    {
        do
        {
            if (reader.HasRows)
            {
                PrintData(reader);
            }
        } while (reader.NextResult());
    }

    Console.WriteLine("Press Enter to finish.");
    Console.ReadLine();
}

private static void PrintData(DataTableReader reader)
{
    // Loop through all the rows in the DataTableReader
    while (reader.Read())
    {
        for (int i = 0; i < reader.FieldCount; i++)
        {
            Console.Write(reader[i] + " ");
        }
        Console.WriteLine();
    }
}

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" });
    return table;
}

private static DataTable GetProducts()
{
    // Create sample Products 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 };
    return table;
}

Private Sub TestHasRows()
   'Retrieve one row from the Store table:
   Dim customerTable As DataTable = GetCustomers()
   Dim productsTable As DataTable = GetProducts()

   Using reader As New DataTableReader( _
      New DataTable() {customerTable, productsTable})

      Do
         If reader.HasRows Then
            PrintData(reader)
         End If
      Loop While reader.NextResult()
   End Using

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

Private Sub PrintData( _
   ByVal reader As DataTableReader)

   ' Loop through all the rows in the DataTableReader.
   Do While reader.Read()
      For i As Integer = 0 To reader.FieldCount - 1
         Console.Write("{0} ", reader(i))
      Next
      Console.WriteLine()
   Loop
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"})
   Return table
End Function

Private Function GetProducts() As DataTable
   ' Create sample Products 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}

   Return table
End Function

Keterangan

Properti HasRows mengembalikan informasi tentang tataan hasil saat ini. DataTableReader Jika berisi beberapa kumpulan hasil, Anda dapat memeriksa nilai HasRows properti segera setelah Anda memanggil NextResult metode untuk menentukan apakah kumpulan hasil baru berisi baris.

HasRows Gunakan properti untuk menghindari persyaratan untuk memanggil Read metode DataTableReader jika tidak ada baris dalam tataan hasil saat ini.

Lihat juga

• NextResult()
• Read()