IDataReader.Read Metode

Definisi

Ruang nama:

System.Data

Rakitan:

System.Data.Common.dll

Memajukan IDataReader ke rekaman berikutnya.

public:
 bool Read();

public bool Read ();

abstract member Read : unit -> bool

Public Function Read () As Boolean

Mengembalikan

Boolean

true jika ada lebih banyak baris; jika tidak, false.

Contoh

Contoh berikut membuat instans dari tiga kelas OleDbConnectionturunan , OleDbCommand, dan OleDbDataReader. Contohnya membaca data, menulisnya ke konsol. Akhirnya, contoh menutup OleDbDataReader, lalu OleDbConnection.

private static void ReadData(string connectionString)
{
    string queryString = "SELECT OrderID, CustomerID FROM Orders";
    using (OracleConnection connection = new OracleConnection(connectionString))
    {
        OracleCommand command = new OracleCommand(queryString, connection);
        connection.Open();
        OracleDataReader reader;
        reader = command.ExecuteReader();

        // Always call Read before accessing data.
        while (reader.Read())
        {
            Console.WriteLine(reader.GetInt32(0) + ", " + reader.GetString(1));
        }

        // Always call Close when done reading.
        reader.Close();
    }
}

Public Sub ReadData(ByVal connectionString As String)
    Dim queryString As String = _
        "SELECT OrderID, CustomerID FROM Orders"

    Using connection As New OracleConnection(connectionString)
        Dim command As New OracleCommand(queryString, connection)
        connection.Open()

        Dim reader As OracleDataReader
        reader = command.ExecuteReader()

        ' Always call Read before accessing data.
        While reader.Read()
            Console.WriteLine(reader.GetInt32(0) & ", " & reader.GetString(1))
        End While

        ' Always call Close when done reading.
        reader.Close()
    End Using
End Sub

Keterangan

Posisi IDataReader default adalah sebelum rekaman pertama. Oleh karena itu, Anda harus memanggil Read untuk mulai mengakses data apa pun.

Saat pembaca data sedang digunakan, koneksi terkait sibuk melayani IDataReader. Ini adalah kasus sampai Close dipanggil.