Writing blobs to files
The following example tries to demonstrate how
OracleBlob can be used to extract blob-data and write it into a file. The example assumes that there is a
table named
tableWithBlob that has (at least) the two columns
filename (a
varchar2) and
image with binary data to be stored in the file named
filename.
// set ORACLE_HOME=c:\oracle\18c
// copy %oracle_home%\ODP.NET\bin\4\Oracle.DataAccess.dll .
// csc -reference:Oracle.DataAccess.dll writeBlobToFile.cs
using System;
using System.Data;
using System.IO;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
class Prg {
static void Main() {
OracleConnection ora = new OracleConnection($"user Id=rene;password=rene;data source=Ora18");
ora.Open();
OracleCommand sql = new OracleCommand("select filename, image from tableWithBlob", ora);
sql.CommandType = CommandType.Text;
OracleDataReader rdr = sql.ExecuteReader();
while (rdr.Read()) {
String filename = rdr.GetString (0);
OracleBlob image = rdr.GetOracleBlob(1);
Console.WriteLine($"{filename}: {image.Length} bytes");
Byte[] bytes = new Byte[image.Length];
int lenRead = image.Read(bytes,0, System.Convert.ToInt32(image.Length ));
if (lenRead != image.Length) {
Console.WriteLine($"! lenRead = {lenRead}");
}
File.WriteAllBytes(filename, bytes);
}
}
}