TdStream Class

Visual Basic
C#
C++/CLI

'Declaration
 
Public NotInheritable Class TdStream 
   Inherits System.IO.Stream
   Implements System.IDisposable

'Usage
 
Dim instance As TdStream

public sealed class TdStream : System.IO.Stream, System.IDisposable

public ref class TdStream sealed : public System.IO.Stream, System.IDisposable

TdStream represents a System.IO.Stream through which raw data (bytes) associated with a BLOB field can be read. Optionally, System.IO.BinaryReader and System.IO.StreamReader is used in conjunction with TdStream for reading of primitive .NET data types. TdStream does not support seeking; an application cannot modify the current position within the stream.

TdStream represents a read-only BLOB and an open query against the Teradata Database when CommandBehavior.SequentialAccess is not requested by the application. This query is separate and distinct from the query associated with the TdDataReader. Therefore the maximum number of open Teradata Database queries (16) limit applies to TdDataReader and TdStream. See TdBlob for additional information.

TdStream implements IDisposable interface. It is highly recommended that Dispose or Close be called before an instance of this class is released for garbage collection. Since garbage collection is not deterministic, valuable Teradata Database resources might not be released immediately. The TdStream is disposed when a TdBlob object is disposed.

The following example returns a TdStream (TdBlob.BaseStream property) representing an Employee picture. It uses a connection to Teradata to execute a query against the Employee table.

C#

public void TdStream GetEmployeePicture(String employeeId, TdConnection cn)
{
    TdCommand cmd = new TdCommand(“Select Pic from Employee Where ID = ?”, cn);
            
    // Initialize the parameter with employee ID.
    TdParameter id = cmd.CreateParameter();
    id.ParameterName = “EmployeeID”;
    id.Direction = System.Data.ParameterDirection.Input;
    id.Value = employeeId;
            
    // Execute the query. Note This example will not work if 
    // CommandBehavior.SequentialAccess is specified since 
    // the reader is Closed/Disposed before the call returns.
    TdDataReader rd = cmd.ExecuteReader();
            
    // Retrieve the picture
    TdBlob employeePicture = rd.GetTdBlob(0);
            
    // Dispose of the reader and command
    rd.Close();
    cmd.Dispose();
    	
    // return the employee picture stream.
    return employeePicture.BaseStream;	
}

System.Object
   System.MarshalByRefObject
      System.IO.Stream
         Teradata.Client.Provider.TdStream

Target Platforms: Windows 7, Windows 8, Windows 8.1, Windows 10, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2

Reference

TdStream Members
Teradata.Client.Provider Namespace
TdBlob Class