dotConnect for PostgreSQL Documentation
Devart.Data.PostgreSql Namespace / PgSqlDataReader Class / GetBytes Method / GetBytes(Int32,Int64,Byte[],Int32,Int32) Method
The zero-based column ordinal.
The index within the field where the read operation is to begin.
The buffer into which to read the stream of bytes.
The index within the buffer where the write operation is to begin.
The maximum length to copy into the buffer.
Example

In This Topic
    GetBytes(Int32,Int64,Byte[],Int32,Int32) Method
    In This Topic
    Reads a stream of bytes from the specified column offset into the buffer as an array starting at the given buffer offset.
    Syntax
    'Declaration
     
    Public Overloads Overrides Function GetBytes( _
       ByVal i As Integer, _
       ByVal fieldOffset As Long, _
       ByVal buffer() As Byte, _
       ByVal bufferOffset As Integer, _
       ByVal length As Integer _
    ) As Long
    public override long GetBytes( 
       int i,
       long fieldOffset,
       byte[] buffer,
       int bufferOffset,
       int length
    )

    Parameters

    i
    The zero-based column ordinal.
    fieldOffset
    The index within the field where the read operation is to begin.
    buffer
    The buffer into which to read the stream of bytes.
    bufferOffset
    The index within the buffer where the write operation is to begin.
    length
    The maximum length to copy into the buffer.

    Return Value

    The actual number of bytes read.

    Remarks
    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 PgSqlDataReader is reading a large data structure into a buffer.

    If you pass a buffer that is a null value, GetBytes returns the length of the field in bytes.

    Example
    This sample shows how to obtain array of bytes from a table and save it to a file.
    static void GetThatBytes(PgSqlConnection pgConnection)
    {
      PgSqlCommand cmd = new PgSqlCommand("SELECT * FROM Test.Dept");
      cmd.Connection = pgConnection;
      pgConnection.Open();
      try
      {
        PgSqlDataReader reader = cmd.ExecuteReader();
        reader.Read();
        byte[] myBytes = new byte[50];
        long bytesRead = reader.GetBytes(reader.GetOrdinal("DName"),0,myBytes,0,50);
        FileStream fs = new FileStream("D:\\Tmp\\1.txt", FileMode.Create);
        fs.Write(myBytes,0,(int)bytesRead);
        fs.Close();
        Console.WriteLine(bytesRead+ " bytes downloaded from table to file.");
        reader.Close();
      }
      finally
      {
        pgConnection.Close();
      }
    }
    Public Sub GetThatBytes(ByVal pgConnection As PgSqlConnection)
      Dim cmd As PgSqlCommand = New PgSqlCommand("SELECT * FROM Test.Dept")
      cmd.Connection = pgConnection
      pgConnection.Open()
      Try
        Dim reader As PgSqlDataReader = cmd.ExecuteReader()
        reader.Read()
        Dim myBytes(50) As Byte
        Dim bytesRead As Long = reader.GetBytes(reader.GetOrdinal("DName"), 0, myBytes, 0, 50)
        Dim fs As FileStream = New FileStream("D:\Tmp\1.txt", FileMode.Create)
        fs.Write(myBytes, 0, Convert.ToInt32(bytesRead))
        fs.Close()
        Console.WriteLine(bytesRead & " bytes downloaded from table to file.")
        reader.Close()
      Finally
        pgConnection.Close()
      End Try
    End Sub
    Requirements

    Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

    See Also