Odp.net Read and write Oracle BLOB fields

DEVELOPER:ODP.NET Serving Winning lobs:

Http://www.oracle.com/technetwork/issue-archive/2005/05-nov/o65odpnet-085139.html

Data Provider for. NET Developer ' s Guide:

https://docs.oracle.com/database/121/ODPNT/OracleBlobClass.htm#ODPNT4035

Read the code for a picture file from the Blob field:

 
 
 1        OracleConnection con = new OracleConnection(connStr);
 2         con.Open();
 3 
 4         // statement to get a blob
 5         string sql = "select yz from sysusers where yhdh=‘123‘";
 6 
 7         // create command object
 8         // InitialLOBFetchSize
 9         //  defaults to 0
10         OracleCommand cmd = new OracleCommand(sql, con);
11 
12         // create a datareader
13         using (OracleDataReader dr = cmd.ExecuteReader())
14         {
15             // read the single row result
16             dr.Read();
17             // use typed accessor to retrieve the blob
18             OracleBlob blob = dr.GetOracleBlob(0);
19 
20             // create a memory stream from the blob
21             using (MemoryStream ms = new MemoryStream(blob.Value))
22             {
23                 // set the image property equal to a bitmap
24                 // created from the memory stream
25                 pictureBox1.Image = new Bitmap(ms);
26             }
27         }

Save the file to the Blob field code:

 
1 con. The Open ();
2
3 // utilize transaction processing (must)
4 OracleTransaction transaction = con.begintransaction ();
5 string SQL ="select yz from sysusers where yhdh= '123' FOR UPDATE";
6 OracleCommand CMD = new OracleCommand(SQL, con);
7
8 using (OracleDataReader reader = cmd.executereader ())
9 {
Obtain the first row of data.
11 reader. The Read ();
12 / / Obtain a LOB.
13 OracleBlob = reader.getoracleblob (0);
14 blob. Erase ();
15 // writes the file to the BLOB
16 byte [] Buffer;
17 FileStream fs = new FileStream(@"d:\01.jpg", filemode. Open);
18 using (MemoryStream ms = new MemoryStream())
19 {
Int b;
21 while ((b = fs.readbyte ())! = 1)
22 {
23 Ms. WriteByte ((byte), b);
24}
25 Buffer = Ms. ToArray ();
26}
27
28 // Begin ChunkWrite to improve performance
29 // Index updates occur only once after EndChunkWrite
30 blob. The Position = 0;
31 blob. BeginChunkWrite (); // it is not necessary to enable BeginChunkWrite, only performance related
32 blob. Write (Buffer, 0, Buffer Length); Write a blob field from byte data
33 blob. EndChunkWrite ();
34 blob. The Close ();
35}
36 // commit the transaction
37 transaction.Com MIT ();
38 con. The Close ();

Odp.net Read and write Oracle BLOB fields