此Web应用程序允许用户更新名为Phonebook的数据库表的名称和电话。
电话簿（UID，姓名，电话）
但是我的代码无法更新它。它显示以下消息。
ERROR: The record is failed to update.
对于这一行，抱歉我没有在此处提供详细信息以保护自己。当我运行实际代码时，包含了信息，我可以成功连接到数据库。
con = DriverManager.getConnection(";databaseName=", "", "");
这是我的更新方法的代码。我真的不知道为什么它运作不好。我希望有人能告诉我哪一行写错了。谢谢！
private void doUpdateEntry(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
out.println("<html>");
out.println("<head>");
out.println("<title>Phonebook</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Phonebook (Update)</h1>");
out.println("<div style='width:600px'>");
out.println("<fieldset>");
String name = request.getParameter("name");
String phone = request.getParameter("phone");
String uid = request.getParameter("uid");
Connection con = null;
out.println("UID: "+uid);
if (name != null && !name.equalsIgnoreCase("") &&
phone != null && !phone.equalsIgnoreCase("") &&
uid != null ) {
// Register the JDBC driver, open a connection
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
con = DriverManager.getConnection(";databaseName=", "", "");
out.println("UID2: "+uid);
// Create a preparedstatement to set the SQL statement
PreparedStatement pstmt = con.prepareStatement("UPDATE [phonebook] SET [Name] = ?, [Phone] = ? WHERE [UID] = ?");
pstmt.setString(1, name);
pstmt.setString(2, phone);
pstmt.setString(3, uid);
// execute the SQL statement
int rows = pstmt.executeUpdate();
out.println("Rows: "+rows);
if (rows > 0) {
out.println("<legend>The record is sucessfully updated.</legend>");
// display the information of the record just added including UID
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("SELECT @@IDENTITY AS [@@IDENTITY]");
if (rs != null && rs.next() != false) {
out.println(rs);
out.println("<p>UID: " + rs.getInt(1) + "</p>");
rs.close();
}
if (stmt != null) {
stmt.close();
}
out.println("<p>Name:" + this.htmlEncode(name) + "</p>");
out.println("<p>Phone Number:" + phone + "</p>");
}
else {
out.println("<legend>ERROR: The record is failed to update.</legend>");
}
}
else {
if (name == null) {
name = "";
}
if (phone == null) {
phone = "";
}
out.println("<legend>Please fill in the form</legend>");
out.println("<form method='POST' action='" + request.getRequestURI() + "'>");
out.println("<input name='action' type='hidden' value='update' />");
out.println("<p>Name:");
out.println("<input name='name' type='text' size='25' maxlength='255' value='" + this.htmlEncode(name) + "' /></p>");
out.println("<p>Phone Number:");
out.println("<input name='phone' type='text' size='8' maxlength='8' value='" + phone + "' /></p>");
out.println("<input name='uid' type='hidden' value='"+uid+"' />");
out.println("<input type='submit' value='Update!' />");
out.println("</form>");
}
out.println("<br/><a href='" + request.getRequestURI() + "'>Back to Phonebook Directory</a>");
out.println("</fieldset>");
out.println("</div>");
out.println("</body>");
out.println("</html>");
} catch (ClassNotFoundException e) {
out.println("<div style='color: red'>" + e.toString() + "</div>");
} catch (SQLException e) {
out.println("<div style='color: red'>" + e.toString() + "</div>");
} finally {
out.close();
}
}