Simple example
The following example selects binary data from a
blob or a
long raw into a
Byte[] and then writes the data into a file.
// set ORACLE_HOME=c:\oracle\18c
// copy %oracle_home%\ODP.NET\bin\4\Oracle.DataAccess.dll .
// csc -reference:Oracle.DataAccess.dll GetBytes.cs
using System;
using System.Data;
using System.IO;
using Oracle.DataAccess.Client;
class Prg {
static void Main() {
OracleConnection ora = new OracleConnection($"user Id=rene;password=rene;data source=Ora18");
ora.Open();
OracleCommand sql = new OracleCommand("select filename, image from tq84_sql_loader_long_raw", ora);
// OracleCommand sql = new OracleCommand("select filename, image from tq84_sql_loader_blob", ora);
sql.CommandType = CommandType.Text;
//
// InitialLONGFetchSize needed if data is select from a LONG RAW (but apparently not
// if selected from a BLOB…)
//
sql.InitialLONGFetchSize = -1;
OracleDataReader rdr = sql.ExecuteReader();
while (rdr.Read()) {
String filename = rdr.GetString(0);
//
// Call GetBytes() with a null Byte[] parameter in order to
// get required length of data:
//
long len = rdr.GetBytes (1, 0, null, 0, 0);
Console.WriteLine($"{filename}: {len} bytes");
//
// Get data as Byte[]:
//
Byte[] bytes = new Byte[len];
rdr.GetBytes(1, 0, bytes, 0, (int) len);
File.WriteAllBytes(filename, bytes);
}
}
}