从数据类型varchar到varbinary（max）的转换（ERROR）

Question

我已经成功地插入和检索了来自java的sql server 中存储为varbinary（max）的图像和文件。我现在要做的是拥有一个允许用户更新文档文件或图像的jframe。

到目前为止，我已经输入了这个。

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    DBConnection db = new DBConnection();
    try {

        File pp = new File(pic);
        FileInputStream fis = new FileInputStream(pp);
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        byte[] buf = new byte[1024];
        for (int readNum; (readNum = fis.read(buf)) != -1;) {

            bos.write(buf, 0, readNum);
        }

        person_image = bos.toByteArray();

    } catch (Exception e) {

    }

    try {

        File ff = new File(fileName);
        FileInputStream fis2 = new FileInputStream(ff);
        ByteArrayOutputStream bos2 = new ByteArrayOutputStream();
        byte[] buf2 = new byte[1024];
        for (int readNum; (readNum = fis2.read(buf2)) != -1;) {

            bos2.write(buf2, 0, readNum);
        }

        docFile = bos2.toByteArray();

    } catch (Exception e) {

    }

    if (txt_doc.getText().isEmpty() || txt_pic.getText().isEmpty()) {
        JOptionPane.showMessageDialog(null, "Cannot have empty fields");
    } else {
        try {

            query = "UPDATE tourClient SET DocumentFile= '" + docFile + "',Photo= '" + person_image + "'WHERE Name= '" + combo_client.getSelectedItem() + "' ";

            PreparedStatement stm = db.getconn().prepareStatement(query);
            int val = stm.executeUpdate();

            if (val > 0) {
                JOptionPane.showMessageDialog(null, "Uploaded successfully!!!");
                rs.next();
            }
            db.getconn().close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }
} 

我收到此错误 - ＆gt;不允许从数据类型varchar到varbinary（max）的隐式转换。使用CONVERT函数运行此查询

我看到过之前提出的一些类似的问题，但我仍然无法纠正我的错误。如果有人能告诉我它的完成情况会很棒。