byte_array_to_blob

// table definition
CREATE TABLE `messages` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `from` int(11) NOT NULL,
  `to` int(11) NOT NULL,
  `content` varbinary(5000) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `to_idx` (`to`),
  KEY `from` (`from`),
  CONSTRAINT `from` FOREIGN KEY (`from`) REFERENCES `users` (`id`),
  CONSTRAINT `to` FOREIGN KEY (`to`) REFERENCES `users` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;


//reading data from database
 String sql = "SELECT content FROM secret_messages.messages where `to`=?";
            Connection con = ds.getCon();
            PreparedStatement ps = con.prepareStatement(sql);
            ps.setInt(1, 4);
            ResultSet rs = ps.executeQuery();
         
            while (rs.next()) {
                //String content=rs.getString(1);
                byte[] content = rs.getBytes("content");// varbinary or blob columns
                try{
                    originalContent = RSA.decrypt(content , privateKey);
                    response.getOutputStream().print("<br/>");
                    response.getOutputStream().print(new String(originalContent));  
                }catch(Exception e){
                    response.getOutputStream().print("Not possile to decript:"+new String(content));  
                    e.printStackTrace();
                }
            }  
            
  //writting data into database
  
  ds = new DataSourceMySQL();
  sql = "insert into messages (`from`,`to`,content) values(?,?,?)";
  con = ds.getCon();
  ps = con.prepareStatement(sql);
  ps.setLong(1, from);
  ps.setLong(2, to);
  //ps.setString(3, content);//byte[] variable
  ps.setBytes(3, messageCyphered);//VARBINARY OR BLOB ON MySQL
  boolean result = ps.execute();