MySqlDataReader Class

MySQL Connector/Net

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

Namespace: MySql.Data.MySqlClient
Assembly: MySql.Data (in MySql.Data.dll) Version: 6.2.2.0

Syntax

C#
public sealed class MySqlDataReader : DbDataReader, IDataReader, IDisposable, IDataRecord

Visual Basic (Declaration)
Public NotInheritable Class MySqlDataReader _ Inherits DbDataReader _ Implements IDataReader, IDisposable, IDataRecord

Visual C++
public ref class MySqlDataReader sealed : public DbDataReader, IDataReader, IDisposable, IDataRecord

Remarks

To create a MySQLDataReader, you must call the ExecuteReader()()() method of the MySqlCommand object, rather than directly using a constructor.

While the MySqlDataReader is in use, the associated MySqlConnection 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 Close()()() method of the MySqlDataReader is called.

IsClosed and RecordsAffected 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 GetValue(Int32) 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.

Examples

The following example creates a MySqlConnection, a MySqlCommand, and a MySqlDataReader. The example reads through the data, writing it out to the console. Finally, the example closes the MySqlDataReader, then the MySqlConnection.

CopyVB.NET

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

CopyC#

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();
}

Inheritance Hierarchy

System..::.Object
  System..::.MarshalByRefObject
    System.Data.Common..::.DbDataReader
      MySql.Data.MySqlClient..::.MySqlDataReader