Inserting BLOB Values with setBlob() Method

JDBC for Oracle - Herong's Tutorial Examples

∟Oracle BLOB (Binary Large Object) - BLOB

∟Inserting BLOB Values with setBlob() Method

This section describes how to insert BLOB values with the PreparedStatement.setBlob() method.

If you want to insert a BLOB column with a character string that comes from a java.sql.Blob object, you can directly set the value with PreparedStatement.setBlob() method.

To test this, I wrote the following program to copy some records with BLOB values as new records back into the same table. During the copy process, the BLOB values are also modified with some Blob object methods - The first 6 bytes are replaced with 0 values.

/* OracleBlobSetBlob.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import java.sql.*;
public class OracleBlobSetBlob {
  public static void main(String [] args) {
    Connection con = null;
    try {
      oracle.jdbc.pool.OracleDataSource ds
        = new oracle.jdbc.pool.OracleDataSource();
      ds.setDriverType("thin");
      ds.setServerName("localhost");
      ds.setPortNumber(1521);
      ds.setDatabaseName("XE");
      ds.setUser("Herong");
      ds.setPassword("TopSecret");
      con = ds.getConnection();

// Deleting records for re-testing
      Statement sta = con.createStatement();
      sta.executeUpdate(
        "DELETE FROM Image WHERE Subject LIKE 'Copy of %'");

// Creating a PreparedStatement for inserting new records
      PreparedStatement ps = con.prepareStatement(
        "INSERT INTO Image (Subject, Body, ID) VALUES (?,?,?)");

// Looping though the first 3 records
      ResultSet res = sta.executeQuery(
        "SELECT * FROM Image ORDER BY ID");
      int i = 0;
      while (res.next() && i<3) {
        i++;
        System.out.println("Copying record ID: "+res.getInt("ID"));
        String subject = res.getString("Subject");
        Blob body = res.getBlob("Body");

// Modifying the Blob object
        byte[] chuck = {(byte)0x00, (byte)0x00, (byte)0x00,
          (byte)0x00, (byte)0x00, (byte)0x00};
        body.setBytes(1,chuck);

// Inserting a new record with setBlob()
        ps.setString(1, "Copy of "+subject);
        ps.setBlob(2,body);
        ps.setInt(3,res.getInt("ID"));
        ps.executeUpdate();
      }
      ps.close();
      res.close();

// Checking the new records
      res = sta.executeQuery(
        "SELECT * FROM Image WHERE Subject LIKE 'Copy of %'");
      while (res.next()) {
        System.out.println("Record ID: "+res.getInt("ID"));
        System.out.println("   Subject = "+res.getString("Subject"));
        byte[] body = res.getBytes("Body");
        String bodyHex = bytesToHex(body, 32);
        System.out.println("   Body in HEX = "+bodyHex+"...");
      }
      res.close();

      sta.close();
      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  public static String bytesToHex(byte[] bytes, int max) {
    StringBuffer buffer = new StringBuffer();
    for (int i=0; i<bytes.length && i<max; i++) {
      buffer.append(Integer.toHexString(bytes[i] & 0xFF));
    }
    return buffer.toString().toUpperCase();
  }
}

Unfortunately, my program failed because Oracle JDBC driver requires that the result set row must be locked:

herong> java -cp .;ojdbc11.jar OracleBlobSetBlob

Copying record ID: 1
java.sql.SQLException:
  ORA-22920: row containing the LOB value is not locked
 at oracle.jdbc.driver.DatabaseError.throwSqlException(
   DatabaseError.java:112)
 at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:331)
 at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:283)
 at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:278)
 at oracle.jdbc.driver.T4C8TTILob.receiveReply(T4C8TTILob.java:930)
 at oracle.jdbc.driver.T4C8TTILob.write(T4C8TTILob.java:249)
 at oracle.jdbc.driver.T4CConnection.putBytes(
   T4CConnection.java:1971)
 at oracle.sql.BLOB.setBytes(BLOB.java:725)
 at OracleBlobSetBlob.main(OracleBlobSetBlob.java:43)

The problem is caused by the Oracle JDBC driver implementation of ResultSet objects. The Blob object returned by getBlob() is still tied up to the ResultSet object. When Blob object is updated, Oracle consider that the ResultSet is updated, which requires locking the row in the database for automatic updates.