Provides a means of reading a forward-only stream of rows from a MySQL database. This class cannot be inherited.

To create a MySQLDataReader, you must call the method of the object, rather than directly using a constructor. While the MySqlDataReader is in use, the associated is busy serving the MySqlDataReader, and no other operations can be performed on the MySqlConnection other than closing it. This is the case until the method of the MySqlDataReader is called. and are the only properties that you can call after the MySqlDataReader is closed. Though the RecordsAffected property may be accessed at any time while the MySqlDataReader exists, always call Close before returning the value of RecordsAffected to ensure an accurate return value. For optimal performance, MySqlDataReader avoids creating unnecessary objects or making unnecessary copies of data. As a result, multiple calls to methods such as return a reference to the same object. Use caution if you are modifying the underlying value of the objects returned by methods such as GetValue. The following example creates a , a , and a MySqlDataReader. The example reads through the data, writing it out to the console. Finally, the example closes the MySqlDataReader, then the MySqlConnection.


        Public Sub ReadMyData(myConnString As String)
        Dim mySelectQuery As String = "SELECT OrderID, CustomerID FROM Orders"
        Dim myConnection As New MySqlConnection(myConnString)
        Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
        myConnection.Open()
        Dim myReader As MySqlDataReader
        myReader = myCommand.ExecuteReader()
        ' Always call Read before accessing data.
        While myReader.Read()
        Console.WriteLine((myReader.GetInt32(0) & ", " & myReader.GetString(1)))
        End While
        ' always call Close when done reading.
        myReader.Close()
        ' Close the connection when done with it.
        myConnection.Close()
        End Sub 'ReadMyData


        public void ReadMyData(string myConnString) {
        string mySelectQuery = "SELECT OrderID, CustomerID FROM Orders";
        MySqlConnection myConnection = new MySqlConnection(myConnString);
        MySqlCommand myCommand = new MySqlCommand(mySelectQuery,myConnection);
        myConnection.Open();
        MySqlDataReader myReader;
        myReader = myCommand.ExecuteReader();
        // Always call Read before accessing data.
        while (myReader.Read()) {
        Console.WriteLine(myReader.GetInt32(0) + ", " + myReader.GetString(1));
        }
        // always call Close when done reading.
        myReader.Close();
        // Close the connection when done with it.
        myConnection.Close();
        }

GetBytes returns the number of available bytes in the field. In most cases this is the exact length of the field. However, the number returned may be less than the true length of the field if GetBytes has already been used to obtain bytes from the field. This may be the case, for example, if the is reading a large data structure into a buffer. For more information, see the SequentialAccess setting for . If you pass a buffer that is a null reference (Nothing in Visual Basic), GetBytes returns the length of the field in bytes. No conversions are performed; therefore the data retrieved must already be a byte array.