oracle 更新 blob 字段的正确方法

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用 mysql 更新一点问题没有。oracle 竟然要先取出来再写入，真是ＳＢ！

 

下面是oracle 更新操作的部分代码代码

 

String sql = " select DEFXPDL from WD_MODELDEFINE  where ProcessID=? for update";
  PreparedStatement ps;
  try {
   Connection conn=derbyUitl.getConnect();
    conn.setAutoCommit(false); // 注意这个否则报 错误

   ps = conn.prepareStatement(sql);
   ps.setString(1, processid);
   ResultSet rs = ps.executeQuery();
   if (rs.next()) {
    // 更新
   
   
        oracle.sql.BLOB    blob = (oracle.sql.BLOB) rs.getBlob("DEFXPDL");
        OutputStream  outStream = blob.getBinaryOutputStream();
        outStream.write(xmlString.getBytes(), 0, xmlString.getBytes().length);
        outStream.flush();
        conn.commit();
        outStream.close();
    

   }

}