BeginExecuteReader() Method

Visual Basic
C#
C++/CLI

'Declaration
 
Public Overloads Function BeginExecuteReader() As IAsyncResult

'Usage
 
Dim instance As TdCommand
Dim value As IAsyncResult
 
value = instance.BeginExecuteReader()

public IAsyncResult BeginExecuteReader()

public:
IAsyncResult^ BeginExecuteReader();

Return Value

Returns a IAsyncResult object.

Exception	Description
System.IndexOutOfRangeException	Indicates the TdParameter.Offset is outside of 0 through array size � 1.
System.InvalidCastException	Indicates one or more parameters cannot be converted to Teradata native types.
System.InvalidOperationException	Can be thrown because of one of the following errors: 1) `TdConnection` is not in Open state or is null or 2) The local transaction associated with the `TdCommand` is not the same local transaction associated with the `TdConnection`. Assign the local transaction to `Transaction` property.
System.ObjectDisposedException	The `TdCommand` is closed / disposed.
TdException	Can be thrown because the Data Provider detected an error.

The call to BeginExecuteReader returns after the request has been successfully sent to Teradata. Any exceptions that are generated by the provider while initializing the request will be thrown during the call to BeginExecuteReader. Exceptions that are generated by the provider or Teradata during the processing of the request will be thrown when TdCommand.EndExecuteReader is called.

The DDL statement CREATE PROCEDURE cannot be specified in an asynchronous execution. If it has been specified a TdException will be thrown when TdCommand.EndExecuteReader is called.

A connection can only have one active request. Therefore, if an asynchronous request is being processed by the provider an exception will be thrown when an attempt is made to start another asynchronous request.

The TdCommand.CommandTimeout property is not applicable to asynchronous execution and will be ignored when a command is asynchronously executed.

Refer to TdCommand.ExecuteReader for more information.

The following example invokes an asynchronous request.

C#

public void BeginExecute(String connectionString, String CommandText,
out TdConnection cn)
{
    cn = new TdConnection(connectionString);
    cn.Open();
    
    IAsyncResult asyncResult;
            
    TdCommand cmd = TdCommand(commandText, cn);
            
     //going to start asynchronous request
     asyncResult = cmd.BeginExecuteReader();
            
     // going to perform other tasks
            
     //going to end the asynchronous request
     //this will also block until processing has completed
     TdDataReader dataReader = cmd.EndExecuteReader(asyncResult);
            
      //RETRIEVE RESULTS FROM TERADATA
            
      cn.Close();
}

Target Platforms: Windows 8.1, Windows 10, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019

Reference

TdCommand Class
TdCommand Members
Overload List